High-strength alloy for additive manufacturing

Abstract

There is provided an aluminum alloy comprising in weight percent: 0.03 – 0.50 Si; 0.03 – 0.30 Fe; 3.5 – 4.9 Cu; 0.2 – 0.7 Mn; 0.05 – 0.20 Mg; 0.35 – 1.0 Ti; 0.05 – 0.35 B; up to 0.50 V; and up to 0.50 Zr. The aluminum alloy comprises TiB2 particles, less than 0.30 wt. % of inevitable impurities and less than 0.10 wt. % of each of the inevitable impurities. The aluminum alloy is particularly useful for additive manufacturing. For example, the aluminum alloy can be deposited layer by layer and then subjected to a thermal consolidation to obtain an aluminum alloy product.

Description

HIGH-STRENGTH ALLOY FOR ADDITIVE MANUFACTURINGCROSS REFERENCE TO A RELATED APPLICATION

[0001] This disclosure claims priority from U.S. provisional application number 63 / 621731 filed January 17, 2024, which is hereby incorporated by reference in its entirety.TECHNICAL FIELD

[0002] This disclosure relates to the field of aluminum alloys, particularly aluminum alloys having improved strength for additive manufacturing.BACKGROUND OF THE ART

[0003] Additive manufacturing (AM) such as selective laser melting (SLM) is a process that has been used to produce metal parts with a complex geometry in a near-net-shape manner. The number of aluminum alloys that can be processed by AM is limited to alloys which can tolerate the challenges of the rapid solidification nature of AM, such as alloys of the Al-Si system. However, the mechanical properties of current Al-Si alloys have limited strength when used in SLM. Currently, Al-Si-Mg feedstocks near the eutectic point are mostly utilized to build crack-free components with high performance. The microstructure determines the mechanical properties of SLM specimens and the microstructure is impacted by the rapid solidification in the SLM process.

[0004] A common problem in all fusion-based AM, such as SLM, is that many aluminum alloys are prone to cracking upon solidification. As a result, eutectic-based aluminum foundry alloys with good castability and fluidity (e.g. AISil OMg and AISi7Mg alloys) have been favoured and used most widely for AM because they resist cracking and offer good printability. Unfortunately, such alloys are known to only achieve mediocre strengths, with yield strengths rarely exceeding 300 MPa. In addition to all these issues, one of the major challenges for high strength alloys is in relation to printability and associated defects such as hot tearing.

[0005] For high Si alloys (4 - 12 wt. %), the Si-based eutectic provides excellent castability and printability. However, these alloys typically achieve yield strengths in the range of 150-300 MPa and therefore do not meet the increasing demand for higher strengths. Higher-strength alloys not only increase the potential for applications where high strengths are essential, but can also be beneficial for more ordinary applications by allowing for extra downgauging, light-weighting and associated cost savings in terms of the required powder quantities and printing times.

[0006] Accordingly, it would be desirable to have new aluminum compositions for AM, for example with reduced Si to limit the drawbacks associated thereto and also to provide improved performance and mechanical properties, including an improved strength with good printability (e.g. avoiding cracking in the microstructure).SUMMARY

[0007] In one aspect, there is provided an aluminum alloy comprising in weight percent: 0.03 - 0.50 Si; 0.03 - 0.30 Fe; 3.5 - 4.9 Cu; 0.2 - 0.7 Mn; 0.05 - 0.20 Mg; 0.35 - 1 .0 Ti; 0.05 - 0.35 B; up to 0.50 V; and up to 0.50 Zr. The aluminum alloy comprises TiB2 particles and less than 0.30 wt. % of inevitable impurities and less than 0.10 wt. % of each of the inevitable impurities. In some embodiments, the aluminum alloy up to 0.3 wt. % of Zn. In some embodiments, the aluminum alloy up to 0.3 Ni. In some embodiments, the TiB2 particles come from a titanium boron grain refiner addition. In some embodiments, the inevitable impurities comprise Sc in a concentration of less than 0.10 wt. %. In some embodiments, the inevitable impurities comprise Ag in a concentration of less than 0.10 wt. %. In some embodiments, the inevitable impurities comprise Li in a concentration of less than 0.10 wt. %. In some embodiments, the Si is present in a concentration of 0.03 - 0.15 wt. %. In some embodiments, the Fe is present in a concentration of 0.10 - 0.20 wt. %. In some embodiments, the Mn is present in a concentration of 0.2 - 0.5 wt. %. In some embodiments, the Mg is present in a concentration of 0.05 - 0.15 wt. %. In some embodiments, the V is present in a concentration of 0.05 - 0.30 wt. %. In some embodiments, the Zr is present in a concentration of 0.05 - 0.50 wt. %. In some embodiments, the Ti is present in a concentration of 0.40 - 1 .0 wt. %.

[0008] In a further aspect, there is provided a method of producing an aluminum alloy product by additive manufacturing, the method comprising: depositing layer by layer the aluminum alloy of the present disclosure; and performing a thermal consolidation to obtain the aluminum alloy product. In some embodiments, the thermal consolidation includes melting each of the layer as the layer is deposited by a laserto perform a laser powder bed fusion. In some embodiments, the method further comprises aging the aluminum alloy product with a T6 or T7 heat treatment. In one example, the T6 heat treatment comprises a first heat treatment at 450-600 °C for 0.1-10 h followed by a second heat treatment of 0.4 to 20 h at 150 to 225 °C. In another example, the T7 heat treatment comprises a first heat performed at 490-500 °C for 0.5-3 h and then a second heat treatment at 515-530 °C for 1-20 h. In some embodiments, the method further comprises a water quench cooling step and optionally an aging step at a temperature of from 175 -225 °C for2- 6 h.

[0009] In a further aspect, there is provided an use of an aluminum alloy in additive manufacturing, wherein the aluminium alloy includes in weight percent: 0.03 - 0.50 Si; 0.03 - 0.30 Fe; 3.5 - 4.9 Cu; 0.2 - 0.7 Mn; 0.05 - 0.20 Mg; 0.05 - 1 .0 Ti; 0.01 - 0.35 B; up to 0.50 V; and up to 0.50 Zr; wherein the aluminum alloy comprises TiB2 particles and less than 0.30 wt. % of inevitable impurities and less than 0.10 wt. % of each of the inevitable impurities

[0010] In still a further aspect, there is provided a method of performing selective laser melting (SLM), the method comprising depositing layer by layer the aluminum alloy as defined in the present invention in powder form and melting each layer as it is deposited using a laser to perform the SLM at an energy density of from 150 to 800 J / mm3and a power of from 100 to 1000 W, for example from 200 to 400 W.

[0011] Many further features and combinations thereof concerning the present improvements will appear to those skilled in the art following a reading of the instant disclosure.DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1A is scanning electron microscopy image of an as cast 224 alloy.

[0013] FIG. 1 B is a microscopy image showing the grains of the as cast 224 alloy.

[0014] FIG. 1 C is a spectrum showing the Al-Cu intermetallic phase of the as cast 224 alloy.

[0015] FIG. 2A is a scanning electron microscopy image of an as cast 224-ZrV alloy.

[0016] FIG. 2B is a microscopy image showing the grains of the as cast 224-ZrV alloy.

[0017] FIG. 2C is a spectrum showing the Al-Cu intermetallic phase of the as cast 224-ZrV alloy.

[0018] FIG. 2D is a spectrum showing the Al-Ti-Zr-V intermetallic phase of the as cast 224- ZrV alloy.

[0019] FIG. 3A is a scanning electron microscopy image of the 224 alloy during surface laser remelting (single scan 300 mm / s).

[0020] FIG. 3B is a scanning electron microscopy image of the 224 alloy during surface laser remelting (single scan 500 mm / s).

[0021] FIG. 3C is a scanning electron microscopy image of the 224 alloy during surface laser remelting (single scan 700 mm / s).

[0022] FIG. 3D is a scanning electron microscopy image of the 224 alloy during surface laser remelting (20 lines scan 500 mm / s).

[0023] FIG. 4A is a scanning electron microscopy image of the 224-ZrV alloy during surface laser remelting (single scan 300 mm / s).

[0024] FIG. 4B is a scanning electron microscopy image of the 224-ZrV alloy during surface laser remelting (single scan 500 mm / s).

[0025] FIG. 4C is a scanning electron microscopy image of the 224-ZrV alloy during surface laser remelting (single scan 700 mm / s).

[0026] FIG. 4D is a scanning electron microscopy image of the 224-ZrV alloy during surface laser remelting (20 lines scan 500 mm / s).

[0027] FIG. 5 is a bar graph showing the hot tearing index (HTI) for the 224 and 224-ZrV alloys.

[0028] FIG. 6A is a scanning electron microscopy image of the as cast 224-3TiB2 alloy.

[0029] FIG. 6B is a microscopy image showing the grain size of the as cast 224-3TiB2 alloy.

[0030] FIG. 6C is a spectrum showing the TiB2 particles of the as cast 224-3TiB2 alloy.

[0031] FIG. 6D is a spectrum showing the Al-Cu intermetallic phases of the as cast 224-3TiB2 alloy.

[0032] FIG. 7A is a scanning electron microscopy image of the 224-3TiB2 alloy during surface laser remelting (single scan 300 mm / s).

[0033] FIG. 7B is a scanning electron microscopy image of the 224-3TiB2 alloy during surface laser remelting (single scan 500 mm / s).

[0034] FIG. 7C is a scanning electron microscopy image of the 224-3TiB2 alloy during surface laser remelting (single scan 700 mm / s).

[0035] FIG. 7D is a scanning electron microscopy image of the 224-3TiB2 alloy during surface laser remelting (20 lines scan 500 mm / s).

[0036] FIG. 8A is a microscopy image showing the as cast 224-ZrV-3TiB2 alloy.

[0037] FIG. 8B is a scanning electron microscopy image of the as cast 224-ZrV-3TiB2 alloy.

[0038] FIG. 8C shows the Al in Fig. 8B.

[0039] FIG. 8D shows the Ti in Fig. 8B.

[0040] FIG. 8E shows the Zr in Fig. 8B.

[0041] FIG. 8F shows the V in Fig. 8B.

[0042] FIG. 8G shows the Cu in Fig. 8B.

[0043] FIG. 9A is a microscopy image showing the as cast 224-ZrV-6TiB2 alloy.

[0044] FIG. 9B is a scanning electron microscopy image of the as cast 224-ZrV-6TiB2 alloy.

[0045] FIG. 9C shows the Al in Fig. 9B.

[0046] FIG. 9D shows the Ti in Fig. 9B.

[0047] FIG. 9E shows the Zr in Fig. 9B.

[0048] FIG. 9F shows the V in Fig. 9B.

[0049] FIG. 9G shows the Cu in Fig. 9B.

[0050] FIG. 10A is a scanning electron microscopy image of the 224-ZrV-6TiB2 alloy during surface laser remelting (single scan 300 mm / s).

[0051] FIG. 10B is a scanning electron microscopy image of the 224-ZrV-6TiB2 alloy during surface laser remelting (single scan 500 mm / s).

[0052] FIG. 10C is a scanning electron microscopy image of the 224-ZrV-6TiB2 alloy during surface laser remelting (single scan 700 mm / s).

[0053] FIG. 10D is a scanning electron microscopy image of the 224-ZrV-6TiB2 alloy during surface laser remelting (20 lines scan 500 mm / s).

[0054] FIG. 11A is a graph of the hardness of 224-3TiB2 alloy in function of aging time at 160°C of T6 treatment time after surface laser remelting.

[0055] FIG. 11B is a graph of the hardness of 224-3TiB2 alloy in function of aging time at 160°C of T5 treatment time after surface laser remelting.

[0056] FIG. 11C is a graph of the hardness of 224-3TiB2 alloy in function of aging time at 160°C of T6 treatment time after casting.

[0057] FIG. 12A is a graph of the hardness of 224-ZrV-6TiB2 alloy in function of aging time at 160°C of T6 treatment time after surface laser remelting.

[0058] FIG. 12B is a graph of the hardness of 224-ZrV-6TiB2 alloy in function of aging time at 160°C of T5 treatment time after surface laser remelting.

[0059] FIG. 12C is a graph of the hardness of 224-ZrV-6TiB2 alloy in function of aging time at 160°C of T6 treatment time after casting.

[0060] FIG. 13 is a graph showing the hardness of the AISi MgMn alloy after solution heat treatment: 500 °C for 2 hours, and T6 aging at 160 °C.

[0061] FIG. 14A is a microscopy image showing the grain structure from center to edge of the melt pool during laser remelting of 224-ZrV alloy with a scan speed of 300 mm / s.

[0062] FIG. 14B is a microscopy image showing the grain structure from center to edge of the melt pool during laser remelting of 224-ZrV-6TiB2 alloy with a scan speed of 300 mm / s.

[0063] FIG. 15A is a microscopy image showing the grain structure in the melt pool center during laser remelting of 224-ZrV alloy and showing a crack.

[0064] FIG. 15B is a graph showing the grain size of 224-ZrV alloy at melt pool center locations and a best fit curve, as in Fig. 15A.

[0065] FIG. 15C is a microscopy image showing the grain structure in the melt pool center during laser remelting of 224-ZrV-6TiB2 alloy and showing no crack.

[0066] FIG. 15D is a graph showing the grain size of 224-ZrV-6TiB2 alloy at melt pool center locations and a best fit curve, as in Fig. 15C.

[0067] FIG. 16A is a graph showing the particle size distribution of the powder alloy used in SLM.

[0068] FIG. 16B is a microscopy image of the particles of the powder alloy used in SLM.

[0069] FIG. 16C is a close-up of Fig. 16B showing a Ti rich particle.

[0070] FIG. 17A is a microscopy image showing the printed sample after SLM at an energy density of 50 J / mm3and 370 W power.

[0071] FIG. 17B is a microscopy image showing the printed sample after SLM at an energy density of 75 J / mm3and 370 W power.

[0072] FIG. 17C is a microscopy image showing the printed sample after SLM at an energy density of 100 J / mm3and 370 W power.

[0073] FIG. 17D is a microscopy image showing the printed sample after SLM at an energy density of 125 J / mm3and 370 W power.

[0074] FIG. 17E is a microscopy image showing the printed sample after SLM at an energy density of 150 J / mm3and 370 W power.

[0075] FIG. 17F is a microscopy image showing the printed sample after SLM at an energy density of 175 J / mm3and 370 W power.

[0076] FIG. 17G is a microscopy image showing the printed sample after SLM at an energy density of 200 J / mm3and 370 W power.

[0077] FIG. 17H is a microscopy image showing the printed sample after SLM at an energy density of 250 J / mm3and 370 W power.

[0078] FIG. 171 is a microscopy image showing the printed sample after SLM at an energy density of 300 J / mm3and 370 W power.

[0079] FIG. 17J is a microscopy image showing the printed sample after SLM at an energy density of 50 J / mm3and 370 W power.

[0080] FIG. 18A is a microscopy image showing the printed sample after SLM at an energy density of 200 J / mm3and 250 W power.

[0081] FIG. 18A is a microscopy image showing the printed sample after SLM at an energy density of 200 J / mm3and 250 W power.

[0082] FIG. 18B is a microscopy image showing the printed sample after SLM at an energy density of 250 J / mm3and 250 W power.

[0083] FIG. 18C is a microscopy image showing the printed sample after SLM at an energy density of 250 J / mm3and 250 W power.

[0084] FIG. 18D is a microscopy image showing the printed sample after SLM at an energy density of 200 J / mm3and 200 W power.

[0085] FIG. 18E is a microscopy image showing the printed sample after SLM at an energy density of 250 J / mm3and 200 W power.

[0086] FIG. 18F is a microscopy image showing the printed sample after SLM at an energy density of 300 J / mm3and 200 W power.DETAILED DESCRIPTION

[0087] Additive manufacturing (AM) is the 3D printing of aluminum components via laser powder bed fusion (LPBF), which is also known as selective laser melting (SLM). There are other forms of AM and the alloys described herein are suitable for all AM, particularly fusion-based AM. A common problem in fusion-based AM is that many aluminum alloys are prone to cracking during rapid solidification. As a result, AISil OMg cast alloys with good castability are most widely used for AM as they resist cracking and offer good printability. However, such Al-Si-based alloys are known to only achieve moderate strengths. It would therefore be desirable to have alloys that can achieve higher strengths with good printability. Al-Cu 224 cast alloys generally exhibit the highest strengths at ambient and elevated temperatures among all cast alloys, but they suffer from poor castability and have high crack susceptibility. They are thus not suitable for fusion based AM such as LPBF.

[0088] The present disclosure provides aluminum alloys that overcome these disadvantages and achieve improved strength, particularly when compared to traditional Al-Cu 224 andAISi Mg alloys. The present aluminum alloys achieved the presently described advantages by providing an addition of titanium boron grain refiner (e.g. TiB2) while maintaining high strengths using the surface laser remelting technique. The present alloys can not only reduce and preferably eliminate solidification cracks but also achieve >30% higher Vickers microhardness than a conventional AISil OMg alloy post-T6 heat treatment. In addition, the present alloys achieved improved mechanical and creep properties at elevated-temperature when compared to the aforementioned traditional alloys. The addition of titanium boron grain refiner (e.g. TiB2) in 224 alloys yielded improved microstructure characteristics and mechanical properties. While the titanium boron grain refiner addition is known to refine the cast grain structure in conventional casting, it was found that the titanium boron grain refiner addition simultaneously eliminates solidification cracks and improves the mechanical properties of the alloys for fusion-based AM, particularly SLM. The present inventors have surprisingly found that the addition of titanium boron grain refiner significantly improves the alloy printability, microstructure, and mechanical properties in additive manufacturing.

[0089] Si is provided in the present alloy in the range of 0.03 - 0.50 wt. %. Si is generally detrimental to the ductility. However it reduces the susceptibility to hot tearing and is therefore still included in the amount of at least 0.03 wt. %. Si is provided in a maximum of 0.50 wt. % to avoid the disadvantages mentioned above regarding Si. In some embodiments, the Si is provided in the range of 0.03 - 0.45 wt. %, 0.03 - 0.40 wt. %, 0.03 - 0.35 wt. %, 0.03 - 0.30 wt. %, 0.03 - 0.25 wt. %, 0.04 - 0.45 wt. %, 0.04 - 0.40 wt. %, 0.04 - 0.35 wt. %, 0.04 - 0.30 wt. %, 0.04 - 0.25 wt. %, 0.05 - 0.45 wt. %, 0.05 - 0.40 wt. %, 0.05 - 0.35 wt. %, 0.05 - 0.30 wt. %, 0.05 - 0.25 wt. %, 0.06 - 0.45 wt. %, 0.06 - 0.40 wt. %, 0.06 - 0.35 wt. %, 0.06 - 0.30 wt. %, 0.06 - 0.25 wt. %, 0.07 - 0.45 wt. %, 0.07 - 0.40 wt. %, 0.07 - 0.35 wt. %, 0.07 - 0.30 wt. %, 0.07 - 0.35 wt. %, 0.08 - 0.45 wt. %, 0.08 - 0.40 wt. %, 0.08 - 0.35 wt. %, 0.08 - 0.30 wt. % or 0.08 - 0.35 wt. %.

[0090] Fe is provided in the present alloy in the range of 0.03 - 0.30 wt. %. Fe is detrimental to ductility but decreases hot tearing susceptibility, a minimum of 0.05 Fe is provided to obtain the beneficial properties but a maximum of 0.30 wt. % Fe is contemplated to limit or avoid the detrimental effect on ductility. In some embodiments, the Fe is provided in the range of 0.04 - 0.30 wt. %, 0.05 - 0.30 wt.%, 0.06 - 0.30 wt. %, 0.07 - 0.30 wt. %, 0.08 - 0.30 wt. %, 0.09 - 0.30 wt. %, 0.10 - 0.30 wt. %, 0.05 - 0.28 wt. %, 0.05 - 0.25 wt. %, 0.05 - 0.23 wt. %, 0.05 - 0.20 wt. %, 0.05 - 0.18 wt. %, 0.05 - 0.17 wt. %, 0.05 - 0.15 wt. %, 0.06 - 0.28 wt. %, 0.07 - 0.25 wt. %, 0.08 - 0.23 wt. %, 0.10 - 0.20 wt. %, 0.08 - 0.18 wt. %, 0.10 - 0.18 wt. %, and 0.10 - 0.15 wt. %.

[0091] Cu is provided in the present alloy in the range of 3.5 - 4.9 wt. %. Cu hardens the alloy, contributes to increasing the alloy’s yield strength and resistance but decreases elongation. The upper limit of Cu is 4.9 wt. % because above this concentration it is very difficult to dissolve all of the Cu. There is a trade-off between elongation and strength when considering the concentration of Cu, however, a minimum of 3.5 wt. % of Cu is provided in the alloy to achieve appropriate yield strength and resistance. In some embodiments, the Cu is provided in the range of 3.5 - 4.8 wt. %, 3.5 - 4.7 wt. %, 3.5 - 4.6 wt. %, 3.5 - 4.5 wt. %, 3.6 - 4.9 wt. %, 3.7 - 4.9 wt. %, 3.8 - 4.9 wt. %, 3.9 - 4.9 wt. %, 3.6 - 4.8 wt. %, 3.7 - 4.7 wt. %, 3.8 - 4.6 wt. %, or 3.9 - 4.5 wt. %.

[0092] Mn is provided in the range of 0.2 - 0.7 wt. %. The Mn is provided in a maximum concentration of 0.70 wt. % because above this concentration Mn risks forming coarse intermetallic phases which are undesirable. A minimum of 0.20 wt. % Mn is, however, included because Mn contributes to improving the mechanical properties of the alloy, particularly in conditions of hot temperatures. In some embodiments, the Mn is provided in a concentration of 0.20 - 0.65 wt. %, 0.20 - 0.60 wt. %, 0.20 - 0.55 wt. % or 0.20 - 0.50 wt. %.

[0093] Mg is provided in the range of 0.05 - 0.20 wt. %. Mg has a role in increasing the yield strength and resistance of the alloy at ambient temperature and at elevated temperatures. Magnesium can be increased for high strength and hardness at the expense of ductility. The hot tearing susceptibility also increases with increasing Mg content. The minimum for a significant hardening effect is 0.05 and the maximum in view of the strength-ductility-tearing compromise is 0.20 wt. %. In some embodiments, the Mg is provided in a concentration of 0.05 - 0.19 wt. %, 0.05 - 0.18 wt. %, 0.05 - 0.17 wt. %, 0.05 - 0.16 wt. %, 0.05 - 0.15 wt. %, 0.06 - 0.20 wt. %, 0.07 - 0.20 wt. %, 0.08 - 0.20 wt. %, 0.09 - 0.20 wt. %, 0.10 - 0.20 wt. %, 0.06 - 0.19 wt. %, 0.07 - 0.18 wt. %, 0.08 - 0.17 wt. %, 0.09 - 0.16 wt. %, or 0.10 - 0.15 wt. %.

[0094] The present alloy is characterized by the addition of a titanium boron grain refiner. Ti is preferably added in its grain refiner form (AI-5Ti-1 B or AI-3Ti-1 B). A minimal addition of grain refiner in the form of TiB2 for example can be provided in a concentration of at least 0.05 wt. %, at least 0.07 wt. %, or at least 0.10 wt. %. In preferred embodiments, an excessive amount of TiB2 grain refiner, eventually in form of particles, is provided. This excessive amount can be at least 0.35 wt. %, at least 0.40 wt. % or at least 0.45 wt. % of Ti and at least 0.03 wt. %, at least 0.04 wt. %, at least 0.05 wt. %, at least 0.06 wt. %, or at least 0.07 wt. % of B. These preferred so- called excessive amounts in the alloy were found to avoid cracking during the fusion based AM.Although the SLM parameters can be tuned to avoid cracking, the addition of Ti as a grain refiner in a concentration of more than 0.05 wt. % or preferably 0.35 wt. % or more was found to reduce or eliminate cracking. In one example, a 70 kg / t addition rate of AI-5Ti-1 B would give 0.35 wt. % of Ti and 0.07 wt. % B in the alloy. Accordingly, in some embodiments, an addition of at least 70 kg / t, at least 75 kg / t, at least 80 kg / t or at least 90 kg / t of AI-5Ti-1 B is provided. In some embodiments, from 175 to 225 kg / t of AI-5Ti-1 B is provided. In some embodiments, from 300 to 350 kg / t of AI-3Ti-1 B is provided. A maximum content of 1 wt. % of Ti is contemplated because above this concentration the Ti will create a requirement for very high melting temperature, it could also lead to ductility decreasing coarse Ti-intermetallic species. In addition, it would increase the cost of the alloy. Ti, even in an amount of 0.05 wt. %, improves the grain structure making the grain structure equiaxed and avoiding, reducing or limiting solidification cracks during AM such as SLM. This is actually contrary to conventional alloys which form coarse columnar grains in the melt pools.

[0095] Accordingly, Ti is provided in the range of 0.35 wt. % to 1 wt. % or 0.05 wt. % to 1 wt. %. In some embodiments, the concentration of Ti is of 0.05 wt. % to 0.95 wt. %, 0.10 wt. % to 0.95 wt. %, 0.15 wt. % to 0.95 wt. %,0.20 wt. % to 0.95 wt. %,0.05 wt. % to 0.90 wt. %, 0.05 wt. % to 0.85 wt. %, 0.35 wt. % to 0.95 wt. %, 0.35 wt. % to 0.90 wt. %, 0.35 wt. % to 0.85 wt. %, 0.35 wt. % to 0.80 wt. %, 0.35 wt. % to 0.75 wt. %, 0.35 wt. % to 0.70 wt. %, 0.40 wt. % to 1 wt. %,0.40 wt. % to 0.95 wt. %, 0.40 wt. % to 0.90 wt. %, 0.40 wt. % to 0.85 wt. %, 0.40 wt. % to 0.75 wt. %, 0.40 wt. % to 0.70 wt. %, 0.45 wt. % to 0.95 wt. %, 0.45 wt. % to 0.90 wt. %, 0.45 wt. % to 0.85 wt. %, 0.45 wt. % to 0.75 wt. %, 0.45 wt. % to 0.70 wt. %, 0.50 wt. % to 0.95 wt. %, 0.50 wt.% to 0.90 wt. %, 0.50 wt. % to 0.85 wt. %, 0.50 wt. % to 0.75 wt. %, or 0.50 wt. % to 0.70 wt. %.Further, the B is provided in the range of 0.05 - 0.35 wt. %. In some embodiments, the concentration of B is of 0.01 - 0.35 wt. %, 0.02 - 0.35 wt. %, 0.03 - 0.35 wt. %,0.01 - 0.30 wt. %,0.02 - 0.30 wt. %, 0.03 - 0.30 wt. %, 0.06 - 0.35 wt. %, 0.07 - 0.35 wt. %, 0.08 - 0.35 wt. %,0.09 - 0.35 wt. %, 0.10 - 0.35 wt. %, 0.05 - 0.33 wt. %, 0.06 - 0.33 wt. %, 0.07 - 0.33 wt. %,0.08 - 0.33 wt. %, 0.09 - 0.33 wt. %, 0.10 - 0.33 wt. %, 0.05 - 0.30 wt. %, 0.06 - 0.30 wt. %,0.07 - 0.30 wt. %, 0.08 - 0.30 wt. %, 0.09 - 0.30 wt. %, 0.10 - 0.30 wt. %, 0.05 - 0.25 wt. %,0.06 - 0.25 wt. %, 0.07 - 0.25 wt. %, 0.08 - 0.25 wt. %, 0.09 - 0.25 wt. %, or 0.10 - 0.25 wt. %.

[0096] V is provided in the present alloy in the range of up to 0.50 wt. %. V has the role of improving the high temperature creep strength of the alloy. V provides beneficial properties at a concentration of up to 0.50 wt.% and this upper limit is because more than 0.50 wt. % would jeopardize the alloy’s peritectic stability and would favourthe formation of an AIV phase containingAIV3 intermetallic compound. A low V addition is also helpful in case of problems with coarse Ti- V-B clusters / agglomerations. It could also be adequate for applications requiring good mechanical properties only at room temperature. Increasing the concentration of V could improve high temperature properties after additive manufacturing where the rapid solidification rates can place more V in solution. However, too high a concentration of V would create a requirement for higher casting temperatures. In some embodiments, the concentration of V is up to 0.45 wt. %, up to 0.40 wt. %, up to 0.35 wt. %, up to 0.30 wt. %, up to 0.25 wt. %, up to 20 wt. %, from 0.05 to 0.50 wt. %, from 0.05 to 0.45 wt. %, from 0.05 to 0.40 wt. %, from 0.05 to 0.35 wt. %, from 0.05 to 0.30 wt. %, from 0.05 to 0.25 wt. %, from 0.05 to 0.20 wt. %, from 0.06 to 0.30 wt. %, from 0.07 to 0.30 wt. %, from 0.08 to 0.30 wt. %, from 0.09 to 0.30 wt. %, from 0.10 to 0.30 wt. %.

[0097] Zr is provided in the present alloy in the range of up to 0.50 wt. %. Zr is provided to improve the high temperature creep strength, and its effect is additive to that of V. Low Zr additions are adequate for applications requiring good mechanical properties only at room temperature. Increasing the upper limit could improve high temperature properties after additive manufacturing where the rapid solidification rates can place more Zr in solution. However, adding too much Zr (more than 0.50 wt. %) would create a requirement for higher casting temperatures and could cause ductility problems due to large brittle AhZr particles that could form in some conditions. In some embodiments, Zr is provided in the concentration of up to 0.45 wt. %, up to 0.40 wt. %, up to 0.35 wt. %, up to 0.30 wt. %, up to 0.25 wt. %, from 0.05 to 0.50 wt. %, from 0.05 to 0.45 wt. %, from 0.05 to 0.40 wt. %, from 0.05 to 0.35 wt. %, from 0.10 to 0.50 wt. %, from 0.10 to 0.45 wt. %, from 0.10 to 0.40 wt. %, or from 0.10 to 0.35 wt. %.

[0098] Ni is an optional and can be excluded from the present alloy. Ni can contribute to the general strength of the alloy particularly at elevated temperatures but also significantly reduces elongation. Since the strength improvement is achieved by other elements in the present alloy the addition of Ni is not necessary and, in some cases, can be avoided due to its negative effect on elongation. In some embodiments, Ni is provided in a concentration of up to 0.3 wt. %, up to 0.25 wt. %, up to 0.20 wt. %, up to 0.15 wt. %, up to 0.10 wt. %, from 0.05 - 0.30 wt. %, from 0.05 - 0.25 wt. %, from 0.05 - 0.20 wt. %, from 0.05 - 0.15 wt. % or from 0.05 - 0.10 wt. %. In other embodiments, the Ni is provided in a concentration of less than 0.05 wt. %, less than 0.04 wt. %, less than 0.03 wt. %, less than 0.02 wt. %, or less than 0.01 wt. %.

[0099] Zn is optional and can be excluded from the present alloy. In some embodiments, Zn is part of the impurities because Zn can decrease the mechanical properties of the alloy andincrease oxidation. Zn is often present in recycled metals, and it is possible to tolerate up to 0.30 wt. % in order to utilize recycled metals. High concentrations of Zn are not desirable because it can evaporate easily during LBPF. However, Zn is not a deliberate addition and can be of up to 0.3 wt. %, up to 0.25 wt. %, up to 0.20 wt. %, up to 0.15 wt. %, up to 0.10 wt. %, from 0.05 - 0.30 wt. %, from 0.05 - 0.25 wt. %, from 0.05 - 0.20 wt. %, from 0.05 - 0.15 wt. % or from 0.05 - 0.10 wt. %. In other embodiments, the Zn is provided in a concentration of less than 0.05 wt. %, less than 0.04 wt. %, less than 0.03 wt. %, less than 0.02 wt. %, or less than 0.01 wt. %.

[0100] Li is optional and can be excluded because it can evaporate easily during LBPF. In some embodiments, the present alloy contains less than 0.10 wt. %, less than 0.09 wt. %, less than 0.08 wt. %, less than 0.07 wt. %, less than 0.06 wt. %, less than 0.05 wt. %, less than 0.04 wt. %, less than 0.03 wt. %, less than 0.02 wt. %, less than 0.01 wt. % or less than 0.005 wt. % of Li.

[0101] Sc is optional and can be excluded in the present alloy. Sc is an expensive grain refiner which is not needed in view of the titanium boron grain refiner additions. A small amount of Sc may optionally be included to provide some benefits in terms of properties and strength. In some embodiments, the present alloy contains less than 0.10 wt. %, less than 0.09 wt. %, less than 0.08 wt. %, less than 0.07 wt. %, less than 0.06 wt. %, less than 0.05 wt. %, less than 0.04 wt. %, less than 0.03 wt. %, less than 0.02 wt. %, or less than 0.01 wt. % of Sc.

[0102] The weight percentage concentrations for the aluminum alloy are provided with the balance being aluminum and inevitable impurities. In some embodiments, each of the inevitable impurity is present at a maximum of 0.1 (and in some embodiments 0.05 or even 0.03) and the total inevitable impurities comprise less than or equal to 0.30. In some embodiments, it is to be understood herein that the term “inevitable impurity” means that there was no deliberate addition of the recited element.

[0103] Ag can be excluded in the present alloy or may be one of the impurities. In some embodiments, the present alloy contains less than 0.1 wt. %, less than 0.09 wt. %, less than 0.08 wt. %, less than 0.07 wt. %, less than 0.06 wt. %, less than 0.05 wt. %, less than 0.04 wt. %, less than 0.03 wt. %, less than 0.02 wt. %, less than 0.01 wt. % or less than 0.005 wt. % of Ag.

[0104] Additive manufacturing, or 3D printing, refers to the layer-by-layer deposition of material to build three-dimensional structures directly from computer-aided design (CAD) files. It enables the fabrication of custom-designed geometrically complex components on a ‘printer’anywhere in the world without the need for large factories, tooling and extensive machining. Compared to traditional ‘subtractive’ manufacturing, this can lead to significant reductions in lead- times, cost and waste for the fabrication of complex bespoke parts, especially for small production runs of highly complex geometries. As a result, additive manufacturing has generated not only a lot of interest and hype, but it has also been transitioning from the realm of rapid prototyping into mainstream manufacturing, with the additive manufacturing industry now experiencing dramatic growth in the sales of ‘printers’ and materials.

[0105] The additive manufacturing process of the present disclosure comprises but is not limited to depositing layer by layer the aluminum alloy described herein in powder form and melting each layer as it is deposited using a laser to perform a laser powder bed fusion. In non- limitative embodiments, the laser power used may be from 100 to 1000 W, from 150 to 750 W, from 200 to 400 W, from 250 to 370 W, or from 300 to 370 W. In non-limitative embodiments, the laser speed may be varied from 100 to 3000 mm / s. In some embodiments, the thickness of the layers deposited are from 0.01 to 0.06 mm, from 0.02 to 0.04 mm or 0.03 mm. In some embodiments, the hatch distance is from 0.10 to 0.15 mm, for example 0.13 mm. The laser spot size can be from 0.050 to 0.150 mm. These parameters may be varied depending on the size and complexity of the specific part being manufactured.

[0106] To obtain improved mechanical properties, a T6 or T7 temperature treatment is performed following manufacturing. The obtained manufactured product is preferably heat treated with a T6 treatment and / or aged. In some embodiments, a stress relief treatment can be performed after manufacturing for 1.5-2.5 h at a temperature of 250-350 °C. In some embodiments, a T6 treatment is performed with an initial treatment at 450-600 °C for 0.1-10 h, 0.1 -1 h or 0.4-0.6 h, followed by cooling (e.g. water quenching (WQ), or quenching with polyethylene glycol, oil, or air / water spray), then optional aging for 20-28 h at room temperature, followed by a final treatment of 0.4 to 20 h or 5 to 7 h at temperature of from 150 to 225 °C or from 150 to 180 °C. Room temperature can be defined as 15-30 °C or 20-25 °C. In some embodiments, the T6 treatment is performed after a stress relief treatment is performed. In general, faster quenching tends to give higher strength, however, in some cases slower quenching can reduce the risk of cracking and distortion due to quench-induced residual stresses. In some embodiments a T7 treatment can be performed. First, solution heat treatment can be performed at around 490- 500 °C for 0.5-3 h and then around 515-530 °C for 1-20 h followed by water quenching at 65 °C for around 24 h at room temperature holding. Aging can be performed at a temperature of from 175 - 225 °C for 2 - 6 h.

[0107] It was presently found that performing SLM with the alloy of the present disclosure can be made without obtaining cracks by employing an energy density of from 150 to 800 J / mm3. In some embodiments, the power used in the SLM is from 100 to 1000 W, from 150 to 750 W, from 200 to 400 W, from 250 to 370 W, or from 300 to 370 W. The scanning speed may vary between 100 and 2000 mm / s. By tuning the parameters of the SLM it was possible to limit or reduce cracking even with relatively lower additions of TiB2. The advantage of the TiB2 addition is however still quite clear as demonstrated in Example 1 .EXAMPLE 1

[0108] A traditional 224 alloy and a 224-ZrV alloy as per WO2011083209 were tested to determine their behavior during surface laser remelting. First, the as-cast microstructure was determined by microscopy and spectroscopy (energy dispersive spectroscopy (EDS)). Similar microstructures were observed for the 224 and 224-Zr alloy (Figs. 1A-1 B and Figs. 2A-2B respectively). Both have relatively large grains, but the grain size appears to be a bit bigger in 224-ZrV (which would correspond to the higher hot tearing sensitivity, see below - perhaps due to Zr poisoning of grain refinement). Grain sizes of both are much larger than for the alloys with extra TiB2 additions. Al-Cu intermetallic species were found in the 224 alloy (Fig. 1 C), and both Al-Cu and Al-Ti-Zr-V intermetallic species were found in the 224-ZrV alloy (Figs. 2C-2D).Table 1. Compositions of 224 alloy and 224-ZrV alloy in weight percent and the balance being aluminum

[0109] Four different surface laser remelting tests were performed, a single scan at 300 mm / s, a single scan at 500 mm / s, a single scan at 700 mm / s and a 20 lines scan at 500 mm / s. Both alloys (224 and 224-ZrV) exhibited a susceptibility to hot tearing during surface laser remelting under all four tested conditions (Figs. 3A-3D and 4A-4D). The 224-ZrV alloy demonstrated a higher susceptibility to hot tearing as per the Easton index relation (Fig. 5). Accordingly, it wasdetermined that significant improvements are needed to render the 224 alloys viable for surface laser remelting and AM.

[0110] The 224 alloy was modified with an addition of TiB2 grain refiner to obtain alloy 224- 3TiB2 as per Table 2. The presence of Al-Cu intermetallic and TiB2 species were confirmed by microscopy and spectroscopy for 224-3TiB2 (Figs. 6A-6D). The grain size was found to be on average around 35 pm (Fig. 6B). The 224-3TiB2 alloy was also tested with the same laser remelting conditions, namely a single scan at 300 mm / s, a single scan at 500 mm / s, a single scan at 700 mm / s and a 20 lines scan at 500 mm / s. The incorporation of TiB2 was surprisingly found to be effective at mitigating cracks during the surface laser remelting process (Figs. 7A-7D).Table 2. Compositions of 224 alloy and 224-3TiB2 alloy in weight percent and the balance being aluminum

[0111] The addition of TiB2 was also tested on the 224-ZrV to obtain alloys 224-ZrV-3TiB2 and 224-ZrV-6TiB2 (Table 3). The grain structure and elemental composition was also confirmed by microscopy (Figs. 8A-8G, and 9A-9G). The grain structure was found to be around 31 pm on average for 224-ZrV-3TiB2 and 32 pm for 224-ZrV-6TiB2 and the elemental composition was confirmed. The alloys were also tested with the same laser remelting conditions, namely a single scan at 300 mm / s, a single scan at 500 mm / s, a single scan at 700 mm / s and a 20 lines scan at 500 mm / s. The incorporation of 0.65 wt. % of Ti (from an AI-5Ti-1 B grain refiner addition giving many TiB2 particles) was observed to effectively mitigate the heightened susceptibility to hot tearing in the 224-ZrV alloy (Figs. 10A-10D). The presence of the TiB2 grain refiner enabled successful solidification during the tested conditions of surface laser remelting without any significant defects. In summary, the solidification of 224-3TiB2 and 224-ZrV-6TiB2 occurred without cracking after the surface laser remelting process. Consequently, a comparative assessment of the mechanical properties of these allows was then performed.Table 3. Compositions of 224-ZrV alloy, 224-ZrV-3TiB2 and 224-ZrV-6TiB2 alloy in weight percent and the balance being aluminum

[0112] The mechanical properties were evaluated after a T5 and a T6 temperature treatment (530 °C for 10h, then water quenching and aging at 160 °C). The hardness measurements were done on 20 lines of scanning. The 224-ZrV-6TiB2 alloy demonstrated the highest hardness in the T6 condition (Figs. 11A-11C, and 12A-12C) achieving around 130 HV. This is an enhanced hardness when compared to conventional AISiMg alloys (hardness increased by about 15-30%). The T6 temper resulted in the best mechanical properties for both alloys after laser surface remelting. The hardness was also compared to that of the AISil OMgMn alloy (Table 4 and Fig. 13) following the surface laser remelting process. The 224-ZrV-6TiB2 alloy outperformed AISilOMgMn in terms of hardness (and the AISil OMgMn hardness is already higher than that of a typical AISi1 OMg alloy). Accordingly, this alloy was selected for further investigation.Table 4. Composition of AISilOMgMn alloy

[0093] The grain size around the melt pool was evaluated (scan speed of 300 mm / s) for alloys 224-ZrV and 224-ZrV-6TiB2 (respectively Figs. 14A-14B). TiB2 particles act as heterogenous nucleation sites for solidification, such that the grains in the pool of alloy 224-ZrV-6TiB2 are much finer and equiaxed when compared to 224-ZrV. The mean grain size was 15.4 pm for 224-ZrV while the mean grain size of 224-ZrV-6TiB2 was 3.6 pm (Figs. 15A-15D). Thus, TiB2 can control the initiation and propagation of cracks during the solidification. In conclusion, the highesthardness achieved was with alloy 224-ZrV-6TiB2 under the T6 condition and with no significant defects present in the melt pool.EXAMPLE 2

[0113] Example 1 used laser remelting as a method to predict the alloy’s potential for SLM. The alloy with the composition summarized in Table 5 was then tested in SLM.Table 5. SLM alloy in wt. % with the balance being Al

[0114] In order to be utilized in SLM the alloy had to be reduced in powder form. The particle size distribution is shown in Fig. 16A and Fig. 16B shows that some irregularly shaped particles were obtained which may affect the flowability of the powder and alter the melting and solidification behaviour during SLM. When producing the powder and adding the TiB2 grain refiner there is some loss in TiB2 which does not get incorporated into the powder. In particular, the amount of boron incorporated was less than expected. The composition in Table 5 is the composition of the alloy as a powder (i.e. accounting for the loss of TiB2). The polished powder contained Ti rich particle as identified in Fig. 16C.

[0115] The SLM parameters of 21 runs are presented in Table 6.Table 6. SLM parameters

[0116] Cracks were found in the printed samples at low energy densities however as the energy density was increased, the cracks were reduced or eliminated (Figs 17A-17J). Samples printed with an energy density of more than 150 J / mm3did not have any cracking. It should be noted that these results were obtained with a low boron incorporation in the powder (0.035 wt. %) and that cracking is not expected at higher TiB2 concentrations such as those demonstrated in Example 1 . However, Example 2 does show the possibility to eliminate cracking with a lower content of TiB2 by optimizing the parameters of the SLM. As shown in Figs. 18A-18F, in both 200W and 250W no cracking was observed. This is a surprising finding as it was previously thought that energy densities of 1700 J / mm3were required to eliminate cracking for Al-Si-Mg alloys in SLM.

Claims

WHAT IS CLAIMED IS:1 . An aluminum alloy comprising in weight percent:0.03 - 0.50 Si;0.03 - 0.30 Fe;3.5 - 4.9 Cu;0.2 - 0.7 Mn;0.05 - 0.20 Mg;0.35 - 1.0 Ti;0.05 - 0.35 B; up to 0.50 V; and up to 0.50 Zr; wherein the aluminum alloy comprises TiB2 particles and less than 0.30 wt. % of inevitable impurities and less than 0.10 wt. % of each of the inevitable impurities.

2. The aluminum alloy of claim 1 , further comprising up to 0.3 wt. % of Zn.

3. The aluminum alloy of claim 1 or 2, further comprising up to 0.3 Ni.

4. The aluminum alloy of any one of claims 1 to 3, wherein the TiB2 particles come from a titanium boron grain refiner addition.

5. The aluminum alloy of any one of claims 1 to 4, wherein the inevitable impurities comprise Sc in a concentration of less than 0.10 wt. %.

6. The aluminum alloy of any one of claims 1 to 5, wherein the inevitable impurities comprise Ag in a concentration of less than 0.10 wt. %.

7. The aluminum alloy of any one of claims 1 to 6, wherein the inevitable impurities comprise Li in a concentration of less than 0.10 wt. %.

8. The aluminum alloy of any one of claims 1 to 7, wherein the Si is present in a concentration of 0.03 - 0.15 wt. %.

9. The aluminum alloy of any one of claims 1 to 8, wherein the Fe is present in a concentration of 0.10 - 0.20 wt. %.

10. The aluminum alloy of any one of claims 1 to 9, wherein the Mn is present in a concentration of 0.2 - 0.5 wt. %.11 . The aluminum alloy of any one of claims 1 to 10, wherein the Mg is present in a concentration of 0.05 - 0.15 wt. %.

12. The aluminum alloy of any one of claims 1 to 11 , wherein the V is present in a concentration of 0.05 - 0.30 wt. %.

13. The aluminum alloy of any one of claims 1 to 12, wherein the Zr is present in a concentration of 0.05 - 0.50 wt. %.

14. The aluminum alloy of any one of claims 1 to 13, wherein the Ti is present in a concentration of 0.40 - 1 .0 wt. %.

15. A method of producing an aluminum alloy product by additive manufacturing, the method comprising: depositing layer by layer an aluminum alloy as defined in any one of claims 1 to 14; and performing a thermal consolidation to obtain the aluminum alloy product.

16. The method of claim 15, wherein the thermal consolidation includes melting each layer as it is deposited by a laser to perform a laser powder bed fusion.

17. The method of claim 15 or 16, further comprising aging the aluminum alloy product with a T6 or T7 heat treatment.

18. The method of claim 17, wherein the T6 heat treatment comprises a first heat treatment at 450-600 °C for 0.1-10 h followed by a second heat treatment of 0.4 to 20 h at 150 to 225 °C.

19. The method of claim 17, wherein the T7 heat treatment comprises a first heat performed at 490-500 °C for 0.5-3 h and then a second heat treatment at 515-530 °C for 1-20 h.

20. The method of any one of claims 15 to 19, further comprising a water quench cooling step.21 . The method of claim 20, further comprising aging at a temperature of from 175 - 225 °C for 2 - 6 h.

22. Use of an aluminum alloy in additive manufacturing, wherein the aluminium alloy includes in weight percent:0.03 - 0.50 Si;0.03 - 0.30 Fe;3.5 - 4.9 Cu;0.2 - 0.7 Mn;0.05 - 0.20 Mg;0.05 - 1.0 Ti;0.01 - 0.35 B; up to 0.50 V; and up to 0.50 Zr; wherein the aluminum alloy comprises TiB2 particles and less than 0.30 wt. % of inevitable impurities and less than 0.10 wt. % of each of the inevitable impurities.

23. A method of performing selective laser melting (SLM), the method comprising depositing layer by layer the aluminum alloy as defined in claim 22 in powder form and melting each layer as it is deposited using a laser to perform the SLM at an energy density of from 150 to 800 J / mm3and a power of from 100 to 1000 W.

24. The method of claim 23, wherein the power is from 200 to 400 W.

25. A method of producing an aluminum alloy product by additive manufacturing, the method comprising: depositing layer by layer an aluminum alloy, wherein the aluminium alloy includes in weight percent:0.03 - 0.50 Si;0.03 - 0.30 Fe;3.5 - 4.9 Cu;0.2 - 0.7 Mn;0.05 - 0.20 Mg;0.05 - 1.0 Ti;0.01 - 0.35 B; up to 0.50 V; and up to 0.50 Zr; wherein the aluminum alloy comprises TiB2 particles and less than 0.30 wt. % of inevitable impurities and less than 0.10 wt. % of each of the inevitable impurities; and performing a thermal consolidation to obtain the aluminum alloy product.

26. The method of claim 25, wherein the thermal consolidation includes melting each layer as it is deposited by a laser to perform a laser powder bed fusion.

27. The method of claim 25 or 26, further comprising aging the aluminum alloy product with a T6 or T7 heat treatment.

28. The method of claim 27, wherein the T6 heat treatment comprises a first heat treatment at 450-600 °C for 0.1-10 h followed by a second heat treatment of 0.4 to 20 h at 150 to 225 °C.

29. The method of claim 27, wherein the T7 heat treatment comprises a first heat performed at 490-500 °C for 0.5-3 h and then a second heat treatment at 515-530 °C for 1-20 h.

30. The method of any one of claims 25 to 29, further comprising a water quench cooling step.31 . The method of claim 30, further comprising aging at a temperature of from 175 - 225 °C for 2 - 6 h.

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