Heat-resistant high-strength piston aluminum alloy and preparation method thereof

Abstract

The present invention provides a heat-resistant high-strength piston aluminum alloy and a preparation method thereof. The heat-resistant high-strength piston aluminum alloy comprises an α-Al phase, a β-Si phase, an in-situ generated nano-Ni-rich phase, a C-TiB2 seed and a B-TiC seed. Among them, the C-TiB2 seed is a C-doped TiB2 seed; the B-TiC seed is a B-doped TiC seed. A portion of the C-TiB2 seed and the B-TiC seed are dispersedly distributed and play the role of nucleation substrate of α-Al grains, while the other portion of the two seeds are in a linear cluster configuration and extend in three dimensions, which can play the role of connecting the heat-resistant phase of the intermetallic compound to promote the three-dimensional configuration. The heat-resistant high-strength piston aluminum alloy according to the present invention can significantly improve the high-temperature mechanical properties.

Description

Technical Field

[0001] The invention relates to the field of metal materials, and in particular to a heat-resistant high-strength piston aluminum alloy and a preparation method thereof. Background Art

[0002] Al-Si alloys are widely used in manufacturing key engine parts such as pistons and cylinders due to their low density, excellent casting performance, good wear resistance, good volume stability and low cost. At the same time, with the increasing requirements for lightweight development and energy conservation and emission reduction, higher and higher requirements are placed on the mechanical properties of Al-Si piston alloy materials, especially the high-temperature comprehensive mechanical properties.

[0003] Al-Si multi-component alloys can be regarded as in-situ self-generated composite materials, and their strengthening effect depends on the volume fraction, shape factor and distribution of the reinforcement. During the solidification process of Al-Si multi-component alloys, blocky ε-Al3Ni, strip-like δ-Al3CuNi, skeletal γ-Al7Cu4Ni and α-Al(Fe,Cr)Si high-temperature strengthening phases are precipitated, and they are distributed in a semi-closed network in the alloy matrix, playing a role in strengthening the skeleton of the alloy.

[0004] However, the brittle Si phase in the Al-Si multi-element alloy structure is a weak link in the high-temperature service process. Its large presence will inevitably cause the improvement of the alloy's high-temperature strength and toughness to encounter insurmountable obstacles and bottlenecks. On the one hand, the coarse brittle Si phase is a weak link in the high-temperature service process and an important source of fatigue crack initiation and fracture; on the other hand, due to the segmentation of coarse and irregular eutectic Si, the heat-resistant phase of the intermetallic compound is difficult to form a closed configuration, and is often dominated by an open or semi-closed configuration, and the configuration control is very difficult. Therefore, traditional Al-Si multi-element alloys are difficult to adapt to the increasingly harsh service environment of high-power density engines, and it is even more difficult to meet the increasingly stringent requirements for high-temperature mechanical properties. Summary of the invention

[0005] The present invention provides a heat-resistant high-strength piston aluminum alloy capable of significantly improving high-temperature mechanical properties and a preparation method thereof.

[0006] According to one aspect of the present invention, a heat-resistant and high-strength piston aluminum alloy is provided, which comprises an α-Al phase, a β-Si phase, an in-situ generated nano-Ni-rich phase, a C-TiB2 seed and a B-TiC seed, wherein the C-TiB2 seed is a C-doped TiB2 seed, the B-TiC seed is a B-doped TiC seed, and a portion of the C-TiB2 seed and the B-TiC seed are dispersedly distributed and serve as nucleation cores of α-Al grains.

[0007] Optionally, based on 100wt% of the heat-resistant high-strength piston aluminum alloy, the content of Si is 10.5wt%-13.5wt%.

[0008] Optionally, the size of the nano Ni-rich phase is less than 500 nm, the nano Ni-rich phase further contains Cu element, and at least a portion of the nano Ni-rich phase is distributed between the β-Si phases.

[0009] Optionally, the C-TiB2 seed crystal and the B-TiC seed crystal are of submicron scale, and another portion of the C-TiB2 seed crystal and the B-TiC seed crystal are in a linear cluster configuration and extend in three dimensions.

[0010] Optionally, based on 100wt% of the heat-resistant and high-strength piston aluminum alloy, the total content of the C-TiB2 seed crystals and the B-TiC seed crystals is 0.01wt%-3.00wt%, based on 100wt% of the C-TiB2 seed crystals, the C doping amount is less than or equal to 2wt%, and based on 100wt% of the B-TiC seed crystals, the B doping amount is less than or equal to 5wt%.

[0011] Optionally, the heat-resistant high-strength piston aluminum alloy further includes P and at least one of Cu, Mg, Zr, Fe, Mn, V, Mo, Cr, and Sc, wherein, based on 100wt% of the heat-resistant high-strength piston aluminum alloy, the content of P is 0.01wt%-0.04wt%, the content of Cu is 1.5wt%-3.5wt%, the content of Mg is 0.5wt%-1.0wt%, the content of Zr is 0.10wt%-0.18wt%, the content of Fe is less than or equal to 1.0wt%, and the content of a single element of Mn, V, Mo, Cr, and Sc is less than or equal to 0.2wt%. The heat-resistant high-strength piston aluminum alloy further includes Ni other than the nano-Ni-rich phase, and based on 100wt% of the heat-resistant high-strength piston aluminum alloy, the total content of Ni in the nano-Ni-rich phase and Ni other than the nano-Ni-rich phase is 1.5wt%-2.8wt%.

[0012] According to another aspect of the present invention, there is provided a method for preparing the heat-resistant and high-strength piston aluminum alloy as described above, the preparation method comprising: preparing a first melt, adding aluminum into a smelting furnace, heating and melting the aluminum to 750°C-800°C, adding silicon and dissolving it completely; preparing a second melt, adding an Al-TCB seed alloy to the first melt, and keeping the temperature at 750°C-800°C for 1 min-10 min, the Al-TCB seed alloy comprising the C-TiB2 seed and the B-TiC seed; preparing a third melt, adjusting the temperature of the second melt to 820°C-850°C, adding an Al-Ni alloy and dissolving it; adjusting the temperature of the third melt to 730°C-780°C and performing a refining treatment, and casting to obtain the heat-resistant and high-strength piston aluminum alloy.

[0013] Optionally, based on 100wt% of the Al-TCB seed alloy, the total content of the C-TiB2 seed and the B-TiC seed is 0.5wt%-10.0wt%, and the addition amount of the Al-TCB seed alloy is 0.4wt%-30.0wt% of the total amount of the heat-resistant and high-strength piston aluminum alloy.

[0014] Optionally, the step of preparing the third melt also includes: at a temperature of 820°C-850°C, after adding and dissolving the Al-Ni alloy, adding an Al-P seed alloy and adding and dissolving at least one of copper, Al-Fe alloy, Al-Mn alloy, Al-V alloy, Al-Mo alloy, Al-Cr alloy and Al-Sc alloy, and then adjusting the temperature to 750°C-760°C, adding and dissolving magnesium and an Al-Zr alloy.

[0015] Optionally, the step of refining the third melt includes refining the third melt at 730° C.-780° C. for 15 min-30 min.

[0016] The heat-resistant and high-strength piston aluminum alloy according to the present invention may include an in-situ generated nano-Ni-rich phase and C-TiB2 seeds and B-TiC seeds. The nano-Ni-rich phase can play a role of dispersion strengthening, which is beneficial to improving the high-temperature mechanical properties. The C-TiB2 seeds and B-TiC seeds can serve as efficient nucleation cores of α-Al grains, effectively refine the matrix α-Al grains, and achieve the effect of fine grain strengthening.

[0017] According to the present invention, at least a portion of the nano Ni-rich phase is distributed between the eutectic Si, so that the lamellar eutectic Si can be evolved into fine and dispersed particles, reducing the initiation of cracks and fractures at the coarse brittle Si phase interface during high-temperature service, and avoiding the segmentation effect of coarse and irregular eutectic Si, thereby further improving the high-temperature mechanical properties.

[0018] According to the present invention, the C-TiB2 seed crystal and the B-TiC seed crystal are in a linear cluster configuration, and the nano-Ni-rich phase and the granular eutectic Si are extended in three dimensions with the linear cluster configuration as a link, promoting the flexible connection of the in-situ configured intermetallic compound and the granular eutectic Si heat-resistant skeleton, so that the nano-Ni-rich phase, the intermetallic compound heat-resistant phase, and the granular eutectic Si jointly form a closed configuration heat-resistant skeleton. In addition, the configured heat-resistant skeleton can be effectively matched with the refined matrix grains, and the two form a heat-resistant structure that is mutually inclusive and synergistically deformed, thereby greatly improving the high-temperature mechanical properties of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description in conjunction with the accompanying drawings.

[0020] Figure 1 It is a SEM microstructure diagram and an electron probe surface scanning composition analysis diagram of the nano Ni-rich phase and granular eutectic Si generated in situ in the heat-resistant and high-strength piston aluminum alloy according to an embodiment of the present invention.

[0021] Figure 2 It is a SEM microstructure diagram and an electron probe surface scanning composition analysis diagram of the nano Ni-rich phase and seed generated in situ in the heat-resistant high-strength piston aluminum alloy according to an embodiment of the present invention.

[0022] Figure 3 It is a SEM microstructure diagram and an electron probe surface scanning component analysis diagram of dispersed C-doped TiB2 seeds in the heat-resistant and high-strength piston aluminum alloy according to an embodiment of the present invention as the nucleation core of α-Al grains.

[0023] Figure 4 1 is a SEM microstructure diagram of a heat-resistant and high-strength piston aluminum alloy according to an embodiment of the present invention. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0026] Hereinafter, embodiments of the present disclosure will be described as follows with reference to the accompanying drawings.

[0027] However, the present disclosure may be exemplified in many different forms and should not be construed as limited to the specific embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0028] It should be understood that when the terms “include” and / or “comprises” are used in the specification, they list the presence of stated materials and / or components, but do not preclude the presence or addition of one or more other materials and / or components.

[0029] Heat-resistant high-strength piston aluminum alloy

[0030] According to an embodiment of the present invention, the heat-resistant and high-strength piston aluminum alloy may include α-Al phase, β-Si phase, in-situ generated nano-Ni-rich phase, C-TiB2 seeds and B-TiC seeds, wherein the C-TiB2 seeds are C-doped TiB2 seeds and the B-TiC seeds are B-doped TiC seeds.

[0031] Below, we will refer to Figures 1 to 4 The microstructure of the heat-resistant high-strength piston aluminum alloy according to an embodiment of the present invention is described in detail.

[0032] Figure 1 It is a SEM microstructure diagram and an electron probe surface scanning component analysis diagram of the nano Ni-rich phase and granular eutectic Si generated in situ in the heat-resistant high-strength piston aluminum alloy according to an embodiment of the present invention, Figure 2 It is a SEM microstructure diagram of the nano Ni-rich phase and the seed crystal generated in situ in the heat-resistant high-strength piston aluminum alloy according to an embodiment of the present invention and an electron probe surface scanning component analysis diagram, Figure 3 The SEM microstructure diagram and the electron probe surface scanning component analysis diagram of the dispersed C-doped TiB2 seed as the nucleation core of α-Al grains in the heat-resistant high-strength piston aluminum alloy according to the embodiment of the present invention are shown. Figure 4 1 is a SEM microstructure diagram of a heat-resistant and high-strength piston aluminum alloy according to an embodiment of the present invention.

[0033] The heat-resistant high-strength piston aluminum alloy according to the embodiment of the present invention may include α-Al phase, β-Si phase, and in-situ generated nano-Ni-rich phase. Figure 1 As shown in (a) to (e), Figure 1 The black matrix in the figure is the α-Al phase, the light grey granular phase is the eutectic Si, and the phase indicated by the arrow is the nano-Ni-rich phase.

[0034] The heat-resistant high-strength piston aluminum alloy according to the embodiment of the present invention may further include C-TiB2 seeds and B-TiC seeds, wherein the C-TiB2 seeds are C-doped TiB2 seeds, and the B-TiC seeds are B-doped TiC seeds. Figure 2 As shown in (a) and (b), a part of the C-TiB2 seeds and B-TiC seeds can be aggregated together to form a linear cluster configuration, and the nano-Ni-rich phase and granular eutectic Si can be attached to the periphery of the linear cluster configuration formed by the C-TiB2 seeds and B-TiC seeds.

[0035] According to an embodiment of the present invention, another portion of the C-TiB 2 seed crystals and the B-TiC seed crystals may be dispersedly distributed. Figure 3 Dispersively distributed C-doped TiB2 seeds (C-TiB2 seeds) are shown as nucleation cores of α-Al grains. In addition, although not shown, B-TiC seeds can also serve as nucleation cores of α-Al grains.

[0036] The heat-resistant high-strength piston aluminum alloy according to the embodiment of the present invention can improve the heat resistance of the piston aluminum alloy, and a specific description is given below.

[0037] like Figure 1 and Figure 2 As shown in the figure, C-TiB2 seeds and B-TiC seeds can induce the precipitation of nano-Ni-rich phase, which can play a role of dispersion strengthening and is beneficial to improving high-temperature mechanical properties. Figure 1 and Figure 2 As shown in the figure, at least a part of the nano Ni-rich phase is distributed between the eutectic Si, so that the plate-like eutectic Si can be transformed into fine dispersed particles, reducing the initiation of cracks and fractures at the interface of the coarse brittle Si phase during high-temperature service, and avoiding the segmentation effect of the coarse and irregular eutectic Si, thereby further improving the high-temperature mechanical properties. In addition, as Figure 3 As shown, C-TiB2 seeds and B-TiC seeds can serve as efficient nucleation cores for α-Al grains and effectively refine the matrix α-Al grains.

[0038] In addition, if Figure 2 As shown in the figure, the C-TiB2 seed crystals and the B-TiC seed crystals are in a linear cluster configuration, and the nano-Ni-rich phase and the granular eutectic Si are extended three-dimensionally with the linear cluster configuration as a link, promoting the flexible connection between the in-situ configured intermetallic compound and the granular eutectic Si heat-resistant skeleton, so that the nano-Ni-rich phase, the intermetallic compound heat-resistant phase, and the granular eutectic Si jointly form a closed configuration heat-resistant skeleton, as shown in the figure. Figure 4 In addition, Figure 4As shown, the configured heat-resistant skeleton can be effectively matched with the refined matrix grains, and the two form a heat-resistant structure that is mutually inclusive and synergistically deformed, thereby greatly improving the high-temperature mechanical properties of the material.

[0039] According to an embodiment of the present invention, based on 100wt% of the heat-resistant high-strength piston aluminum alloy, the content of Si may be 10.5wt%-13.5wt%. For example, based on 100wt% of the heat-resistant high-strength piston aluminum alloy, the content of Si may be 11.8wt%-12.2wt%.

[0040] According to an embodiment of the present invention, the size of the nano Ni-rich phase is nanoscale, and its size may be less than 500nm. Here, the size of the nano Ni-rich phase may refer to the major axis size or the minor axis size of the nano Ni-rich phase, or may refer to the average value of the major axis size and the minor axis size. As an example, the size of the nano Ni-rich phase may be less than or equal to 450nm. As an example, the size of the nano Ni-rich phase may be greater than or equal to 200nm.

[0041] According to an embodiment of the present invention, Figure 1 As shown, the nano Ni-rich phase may also contain Cu element. Figure 1 and Figure 2 As shown, at least a portion of the nano-Ni-rich phase can be distributed between the β-Si phases, that is, the nano-Ni-rich phase can separate the plate-like β-Si phase, reduce the initiation of cracks and fractures at the coarse brittle Si phase interface during high-temperature service, and avoid the segmentation effect of coarse and irregular eutectic Si.

[0042] According to an embodiment of the present invention, Figure 2 As shown, the C-TiB2 seeds and B-TiC seeds are submicron-sized. The small-sized C-TiB2 seeds and B-TiC seeds can be efficiently used as nucleation cores of α-Al grains, and can give full play to the flexible connection effect of the linear cluster configuration. As an example, the size of the C-TiB2 seeds and B-TiC seeds can be 0.1μm-1μm, or can be 0.1μm-0.5μm. Here, the size of the C-TiB2 seeds and B-TiC seeds can refer to the major axis size or minor axis size of the C-TiB2 seeds or B-TiC seeds, or the average value of the major axis size and the minor axis size.

[0043] According to an embodiment of the present invention, the total content of C-TiB2 seeds and B-TiC seeds is not specifically limited, as long as it can induce the precipitation of nano-Ni-rich phase and serve as the nucleation core of α-Al grains. As an example, based on 100wt% of the heat-resistant high-strength piston aluminum alloy, the total content of C-TiB2 seeds and B-TiC seeds can be 0.01wt%-3.00wt%. If the total content of C-TiB2 seeds and B-TiC seeds is less than 0.01wt% based on 100wt% of the heat-resistant high-strength piston aluminum alloy, the effect of inducing the precipitation of nano-Ni-rich phase and serving as the nucleation core of α-Al grains may be insufficient, resulting in a small improvement in the high-temperature mechanical properties of the piston aluminum alloy. If the total content of C-TiB2 seeds and B-TiC seeds is greater than 3wt% based on 100wt% of the heat-resistant high-strength piston aluminum alloy, continuing to increase the content of the two seeds may not further improve the high-temperature mechanical properties or the improvement is small.

[0044] As an example, based on 100wt% of the heat-resistant high-strength piston aluminum alloy, the total content of C-TiB2 seeds and B-TiC seeds may be 0.05wt%-0.25wt%, 0.25wt%-0.35wt%, 0.4wt%-0.8wt% or 1.0wt%-2.0wt%.

[0045] According to an embodiment of the present invention, based on 100 wt % of the C-TiB2 seed crystal, the C doping amount is less than or equal to 2 wt %. The lower limit of the C doping amount in the C-TiB2 seed crystal is not specifically limited, for example, it can be greater than or equal to 0.002 wt %.

[0046] According to an embodiment of the present invention, based on 100 wt % of the B-TiC seed crystal, the B doping amount is less than or equal to 5 wt %. The lower limit of the B doping amount in the B-TiC seed crystal is not specifically limited, for example, it can be greater than or equal to 0.002 wt %.

[0047] According to an embodiment of the present invention, the heat-resistant high-strength piston aluminum alloy may further include P and at least one of Cu, Mg, Zr, Fe, Mn, V, Mo, Cr, and Sc. Based on 100wt% of the heat-resistant high-strength piston aluminum alloy, the content of P is 0.01wt%-0.04wt%, the content of Cu may be 1.5wt%-3.5wt%, the content of Mg may be 0.5wt%-1.0wt%, the content of Zr may be 0.10wt%-0.18wt%, the content of Fe may be less than or equal to 1.0wt%, and the content of a single element of Mn, V, Mo, Cr, and Sc may be less than or equal to 0.2wt%.

[0048] As an example, based on 100wt% of the heat-resistant and high-strength piston aluminum alloy, the P content is 0.02wt%-0.03wt%, the Cu content can be 2.8wt%-3.5wt%, the Mg content can be 0.7wt%-1.0wt%, the Zr content can be 0.1wt%-0.12wt%, the Fe content can be 0.3wt%-0.4wt%, the Mn content can be 0.1wt%-0.2wt%, and the Cr content can be 0.05wt%-0.1wt%.

[0049] According to an embodiment of the present invention, the heat-resistant high-strength piston aluminum alloy may further include Ni in addition to the nano-Ni-rich phase. That is, a portion of the Ni added to the heat-resistant high-strength piston aluminum alloy may exist in the form of a nano-Ni-rich phase, and another portion may exist in other forms, for example, may be formed in an intermetallic compound and / or solid-dissolved in an Al matrix.

[0050] According to an embodiment of the present invention, based on 100wt% of the heat-resistant high-strength piston aluminum alloy, the total content of Ni in the nano Ni-rich phase and Ni excluding the nano Ni-rich phase may be 1.5wt%-2.8wt%, for example, 1.7wt%-2.0wt%.

[0051] According to the above description, the heat-resistant and high-strength piston aluminum alloy may include an in-situ generated nano-Ni-rich phase and C-TiB2 seeds and B-TiC seeds. The nano-Ni-rich phase can play a role of dispersion strengthening, which is beneficial to improving the high-temperature mechanical properties. In addition, in addition to playing the role of nucleation core refinement of α-Al grains, C-TiB2 seeds and B-TiC seeds can also promote the flexible connection of in-situ configured intermetallic compounds and granular eutectic Si heat-resistant skeletons, so that the nano-Ni-rich phase, the intermetallic compound heat-resistant phase, and the granular eutectic Si jointly form a closed configuration of the heat-resistant skeleton.

[0052] Hereinafter, a method for preparing a heat-resistant high-strength piston aluminum alloy according to an embodiment of the present invention is described. For the sake of brevity, the description repeated in the above content may be omitted.

[0053] Preparation method of heat-resistant high-strength piston aluminum alloy

[0054] The preparation method of the heat-resistant and high-strength piston aluminum alloy according to an embodiment of the present invention may include: preparing a first melt, adding aluminum into a smelting furnace, heating and melting to 750°C-800°C, adding silicon and completely dissolving the silicon; preparing a second melt, adding Al-TCB seed alloy to the first melt, and keeping it warm at 750°C-800°C for 1min-10min, the Al-TCB seed alloy including C-TiB2 seed and B-TiC seed; preparing a third melt, adjusting the temperature of the second melt to 820°C-850°C, adding Al-Ni alloy and dissolving it; adjusting the temperature of the third melt to 730°C-780°C and performing a refining treatment, and casting to obtain the heat-resistant and high-strength piston aluminum alloy.

[0055] First, a first melt is prepared. Specifically, aluminum can be added to a smelting furnace, and when the temperature is raised to 750° C. to 800° C., silicon is added and completely dissolved to form the first melt.

[0056] In the step of preparing the first melt, the raw materials aluminum and silicon may be pure aluminum and pure silicon, respectively, but the present invention is not particularly limited thereto, as long as a first melt containing Al and Si can be formed. In addition, adding silicon when the temperature is raised to 750° C.-800° C. is conducive to the full dissolution of silicon. In addition, stirring (e.g., mechanical or electromagnetic stirring) may be applied to promote the dissolution of silicon.

[0057] Then, prepare a second melt. Specifically, an Al-TCB seed alloy may be added to the first melt and kept at a temperature of 750°C-800°C for 1 min-10 min. The Al-TCB seed alloy may include an Al matrix and C-TiB2 seeds and B-TiC seeds. As an example, based on 100wt% of the Al-TCB seed alloy, the total content of the C-TiB2 seeds and the B-TiC seeds may be 0.5wt%-10.0wt%.

[0058] According to an embodiment of the present invention, the addition amount of the Al-TCB seed alloy can be 0.4wt%-30.0wt% of the total amount of the heat-resistant high-strength piston aluminum alloy. The addition amount of the Al-TCB seed alloy can be adjusted according to the total content of the C-TiB2 seed crystals and the B-TiC seed crystals in the Al-TCB seed alloy, so that based on 100wt% of the heat-resistant high-strength piston aluminum alloy, the total content of the C-TiB2 seed crystals and the B-TiC seed crystals is 0.01wt%-3.00wt%.

[0059] In the step of preparing the second melt, after adding the Al-TCB seed alloy to the first melt, the temperature is kept at 750°C-800°C for 1min-10min, so as to give full play to the role of C-TiB2 seeds and B-TiC seeds as nucleation cores of α-Al grains. If the holding temperature is lower than 750°C or higher than 800°C or the holding time is less than 1min or more than 10min, the α-Al grains may not be fully refined. As an example, after adding the Al-TCB seed alloy to the first melt, it can be kept at 750°C-800°C for 2min-5min. In addition, by keeping the temperature at 750°C-800°C for 1min-10min, the C-TiB2 seeds and B-TiC seeds are fully dissolved in the second melt, which is also conducive to the subsequent full play of the role of inducing the precipitation of nano-Ni-rich phase.

[0060] Next, a third melt can be prepared. Specifically, after the temperature of the second melt is adjusted to 820°C-850°C, an Al-Ni alloy is added and dissolved. Stirring may be applied to promote sufficient dissolution of the Al-Ni alloy, for example, mechanical or electromagnetic stirring may be applied to promote sufficient dissolution of the Al-Ni alloy. Under the induction of C-TiB2 seeds and B-TiC seeds, a nano-Ni-rich phase may be precipitated. As an example, a portion of the added Ni element may form a nano-Ni-rich phase, and another portion of the added Ni element may exist in other forms, for example, may be formed in an intermetallic compound and / or solid-dissolved in an Al matrix. By adding the Al-Ni alloy after adjusting the temperature to 820°C-850°C, the precipitation of the nano-Ni-rich phase is facilitated.

[0061] According to an embodiment of the present invention, other alloying elements may be added as needed. As an example, the step of preparing the third melt may also include: at a temperature of 820°C-850°C, after adding and dissolving the Al-Ni alloy, adding an Al-P seed alloy and adding and dissolving at least one of pure copper, Al-Fe alloy, Al-Mn alloy, Al-V alloy, Al-Mo alloy, Al-Cr alloy and Al-Sc alloy, and then adjusting the temperature to 750°C-760°C, adding and dissolving magnesium and an Al-Zr alloy.

[0062] The addition amount of pure copper, magnesium, Al-Zr alloy, Al-Fe alloy, Al-Mn alloy, Al-V alloy, Al-Mo alloy, Al-Cr alloy, and Al-Sc alloy can be adjusted according to the content of P, Cu, Mg, Zr, Fe, Mn, V, Mo, Cr, and Sc in the heat-resistant high-strength piston aluminum alloy. For example, based on 100wt% of the heat-resistant high-strength piston aluminum alloy, the content of P can be 0.01wt%-0.04wt%, the content of Cu can be 1.5wt%-3.5wt%, the content of Mg can be 0.5wt%-1.0wt%, the content of Zr can be 0.10wt%-0.18wt%, the content of Fe can be less than or equal to 1.0wt%, and the content of each of the individual elements of Mn, V, Mo, Cr, and Sc can be less than or equal to 0.2wt%.

[0063] Finally, the third melt is refined and cast to obtain a heat-resistant high-strength piston aluminum alloy. For example, the third melt can be sampled and tested. After the composition is qualified, the temperature of the third melt is maintained at 730°C-780°C, and the refining treatment is performed for 15min-30min. The alloy composition is tested again, and after it is qualified, it is cast to obtain a heat-resistant high-strength piston aluminum alloy.

[0064] The heat-resistant and high-strength piston aluminum alloy prepared according to the preparation method described above may include an in-situ generated nano-Ni-rich phase and C-TiB2 seeds and B-TiC seeds. The nano-Ni-rich phase can play a role of dispersion strengthening, which is beneficial to improving the high-temperature mechanical properties. In addition, in addition to playing the role of nucleation core refinement of α-Al grains, C-TiB2 seeds and B-TiC seeds can also promote the flexible connection of in-situ configured intermetallic compounds and granular eutectic Si heat-resistant skeletons, so that the nano-Ni-rich phase, the intermetallic compound heat-resistant phase, and the granular eutectic Si jointly form a closed configuration of the heat-resistant skeleton.

[0065] Example 1

[0066] The heat-resistant high-strength piston aluminum alloy of Example 1 has a composition formula based on weight percentage: Al-11.8Si-2.8Cu-1.7Ni-0.7Mg-0.1Zr-0.4Fe-0.2Mn-0.1Cr-0.2(C-TiB2)-0.05(B-TiC). In addition, based on 100wt% of the heat-resistant high-strength piston aluminum alloy, the content of P is 0.02wt%.

[0067] First, raw materials are prepared according to the above composition formula: pure aluminum, pure silicon, Al-TCB seed alloy, Al-Ni alloy, Al-P seed alloy, pure copper, magnesium, Al-Zr alloy, Al-Fe alloy, Al-Mn alloy and Al-Cr alloy.

[0068] In the Al-TCB seed alloy, based on 100wt% of the Al-TCB seed alloy, the total content of C-TiB2 seeds and B-TiC seeds is 1wt%, and the addition amount of the Al-TCB seed alloy is 5wt% of the total weight of the heat-resistant and high-strength piston aluminum alloy.

[0069] Add pure aluminum into the melting furnace, heat it up to 755°C and then add pure silicon into the melt. After the pure silicon is completely dissolved, add Al-TCB seed alloy into the alloy melt and keep it at 760°C for 1 minute.

[0070] The temperature of the above alloy melt is adjusted to 840°C, and Al-Ni alloy, Al-P seed alloy, pure copper, Al-Fe alloy, Al-Mn alloy, and Al-Cr alloy are added, and stirring is applied. After complete dissolution, the melt temperature is adjusted to 750°C, and pure magnesium and Al-Zr alloy are added, and stirring is applied until complete dissolution.

[0071] The above alloy melt was sampled and tested. After the composition was qualified, the melt temperature was maintained at 730°C, the melt was refined for 15 minutes, and the alloy composition was tested again. After passing the test, it was cast to obtain a heat-resistant and high-strength piston aluminum alloy casting.

[0072] The heat-resistant high-strength piston aluminum alloy castings were quenched, and the tensile strength and elongation of the castings in the quenched state were measured.

[0073] The heat-resistant high-strength piston aluminum alloy casting according to Example 1 has a tensile strength of 118 MPa at 350° C. and an elongation of 3.5%.

[0074] Example 2

[0075] The heat-resistant high-strength piston aluminum alloy of Example 2 has a composition formula based on weight percentage: Al-12.2Si-3.5Cu-2.0Ni-0.7Mg-0.12Zr-0.3Fe-0.1Mn-0.1Cr-0.25(C-TiB2)-0.1(B-Ti C). In addition, based on 100wt% of the heat-resistant high-strength piston aluminum alloy, the content of P is 0.02wt%.

[0076] First, raw materials are prepared according to the above composition formula: pure aluminum, pure silicon, Al-TCB seed alloy, Al-Ni alloy, Al-P seed alloy, pure copper, magnesium, Al-Zr alloy, Al-Fe alloy, Al-Mn alloy and Al-Cr alloy.

[0077] In the Al-TCB seed alloy, based on 100wt% of the Al-TCB seed alloy, the total content of C-TiB2 seeds and B-TiC seeds is 3.5wt%, and the addition amount of the Al-TCB seed alloy is 10wt% of the total weight of the heat-resistant and high-strength piston aluminum alloy.

[0078] Add pure aluminum into the smelting furnace, heat it up to 780°C and then add pure silicon into the melt. After the pure silicon is completely dissolved, add Al-TCB seed alloy into the alloy melt and keep it at 790°C for 10 minutes.

[0079] The temperature of the above alloy melt is adjusted to 840°C, and Al-Ni alloy, Al-P seed alloy, pure copper, Al-Fe alloy, Al-Mn alloy, and Al-Cr alloy are added, and stirring is applied. After complete dissolution, the melt temperature is adjusted to 760°C, and pure magnesium and Al-Zr alloy are added, and stirring is applied until complete dissolution.

[0080] The above alloy melt was sampled and tested. After the composition was qualified, the melt temperature was maintained at 760°C, the melt was refined for 25 minutes, and the alloy composition was tested again. After passing the test, it was cast to obtain a heat-resistant and high-strength piston aluminum alloy casting.

[0081] The heat-resistant high-strength piston aluminum alloy castings were quenched, and the tensile strength and elongation of the castings in the quenched state were measured.

[0082] The heat-resistant high-strength piston aluminum alloy casting according to Example 2 has a tensile strength of 123 MPa at 350° C. and an elongation of 3.0%.

[0083] Comparative Example 1

[0084] The heat-resistant high-strength piston aluminum alloy of Comparative Example 1 has a composition formula based on weight percentage: Al-11.8Si-2.8Cu-1.7Ni-0.7Mg-0.1Zr-0.4Fe-0.2Mn-0.1Cr. In addition, based on 100wt% of the heat-resistant high-strength piston aluminum alloy, the content of P is 0.02wt%.

[0085] First, prepare the raw materials according to the above composition formula: pure aluminum, pure silicon, Al-Ni alloy, Al-P seed alloy, pure copper, magnesium, Al-Zr alloy, Al-Fe alloy, Al-Mn alloy and Al-Cr alloy.

[0086] Pure aluminum is added to a smelting furnace, and when the temperature is raised to 755°C, pure silicon is added to the melt and completely dissolved.

[0087] The temperature of the above alloy melt is adjusted to 830°C, and Al-Ni alloy, Al-P seed alloy, pure copper, Al-Fe alloy, Al-Mn alloy, and Al-Cr alloy are added, and stirring is applied. After complete dissolution, the melt temperature is adjusted to 750°C, and pure magnesium and Al-Zr alloy are added, and stirring is applied until complete dissolution.

[0088] The alloy melt is sampled and tested. After the composition is qualified, the melt temperature is maintained at 730°C, the melt is refined for 15 minutes, the alloy composition is tested again, and after passing the test, casting is performed to obtain a casting.

[0089] The castings were quenched and the tensile strength and elongation of the castings in the quenched state were measured.

[0090] The piston aluminum alloy casting according to Comparative Example 1 has a tensile strength of 78 MPa at 350° C. and an elongation of 2.1%.

[0091] Comparative Example 2

[0092] The heat-resistant high-strength piston aluminum alloy of Example 2 has a composition formula based on weight percentage: Al-12.2Si-3.5Cu-2.0Ni-0.7Mg-0.12Zr-0.3Fe-0.1Mn-0.1Cr. In addition, based on 100wt% of the heat-resistant high-strength piston aluminum alloy, the content of P is 0.02wt%.

[0093] First, prepare the raw materials according to the above composition formula: pure aluminum, pure silicon, Al-Ni alloy, Al-P seed alloy, pure copper, magnesium, Al-Zr alloy, Al-Fe alloy, Al-Mn alloy and Al-Cr alloy.

[0094] Pure aluminum is added to a smelting furnace, and when the temperature is raised to 780°C, pure silicon is added to the melt and completely dissolved.

[0095] The temperature of the above alloy melt is adjusted to 830°C, and Al-Ni alloy, Al-P seed alloy, pure copper, Al-Fe alloy, Al-Mn alloy, and Al-Cr alloy are added, and stirring is applied. After complete dissolution, the melt temperature is adjusted to 760°C, pure magnesium and Al-Zr alloy are added, and stirring is applied until complete dissolution.

[0096] The alloy melt is sampled and tested. After the composition is qualified, the melt temperature is maintained at 760°C, the melt is refined for 25 minutes, the alloy composition is tested again, and after passing the test, casting is performed to obtain a casting.

[0097] The castings were quenched and the tensile strength and elongation of the castings in the quenched state were measured.

[0098] The piston aluminum alloy casting according to Comparative Example 2 has a tensile strength of 79 MPa at 350° C. and an elongation of 1.9%.

[0099] The difference between Comparative Example 1 and Example 1 is that the Al-TCB seed alloy is not added and the step of adding the Al-TCB seed alloy is omitted, and the other components and preparation steps are the same. The difference between Comparative Example 2 and Example 2 is that the Al-TCB seed alloy is not added and the step of adding the Al-TCB seed alloy is omitted, and the other components and preparation steps are the same.

[0100] In Examples 1 and 2, Al-TCB seed alloy is added and a coordinated addition process is adopted, so that an in-situ generated nano-Ni-rich phase is formed in the prepared heat-resistant and high-strength piston aluminum alloy, and a portion of the C-TiB2 seed and B-TiC seed are dispersed and used as nucleation cores for α-Al grains.

[0101] In Comparative Examples 1 and 2, no Al-TCB seed alloy is added, so no in-situ generated nano Ni-rich phase is formed in the piston aluminum alloys of Comparative Examples 1 and 2, and no C-TiB2 seed and B-TiC seed are contained.

[0102] Compared with comparative example 1, the tensile strength and elongation of the heat-resistant high-strength piston aluminum alloy in the casting quenching state of embodiment 1 are increased by 51.3% and 66.7%, respectively. In addition, compared with comparative example 2, the tensile strength and elongation of the heat-resistant high-strength piston aluminum alloy in the casting quenching state of embodiment 2 are increased by 55.7% and 36.7%, respectively.

[0103] Therefore, according to the present invention, the heat-resistant high-strength piston aluminum alloy according to the present invention is obtained by adding Al-TCB seed alloy and adopting a coordinated addition process, which can improve the high-temperature tensile strength and elongation.

[0104] The heat-resistant and high-strength piston aluminum alloy according to the present invention described above has at least the following advantages.

[0105] The heat-resistant and high-strength piston aluminum alloy according to the present invention may include an in-situ generated nano-Ni-rich phase and C-TiB2 seeds and B-TiC seeds. The nano-Ni-rich phase can play a role of dispersion strengthening, which is beneficial to improving the high-temperature mechanical properties. The C-TiB2 seeds and B-TiC seeds can serve as efficient nucleation cores of α-Al grains, effectively refine the matrix α-Al grains, and achieve the effect of fine grain strengthening.

[0106] At least a portion of the nano Ni-rich phase is distributed between the eutectic Si, so that the lamellar eutectic Si can evolve into fine and dispersed particles, reducing the initiation of cracks and fractures at the coarse brittle Si phase interface during high-temperature service, and avoiding the segmentation effect of coarse and irregular eutectic Si, thereby further improving the high-temperature mechanical properties.

[0107] The C-TiB2 seed and B-TiC seed are in a linear cluster configuration, and the nano-Ni-rich phase and the granular eutectic Si are extended in three dimensions with the linear cluster configuration as a link, promoting the flexible connection of the in-situ configured intermetallic compound and the granular eutectic Si heat-resistant skeleton, so that the nano-Ni-rich phase, the intermetallic compound heat-resistant phase, and the granular eutectic Si jointly form a closed configuration heat-resistant skeleton. In addition, the configured heat-resistant skeleton can be effectively matched with the refined matrix grains, and the two form a heat-resistant structure that is mutually inclusive and synergistically deformed, thereby greatly improving the high-temperature mechanical properties of the material.

[0108] While exemplary embodiments of the present invention have been described in detail with reference to examples, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the claims.

Claims

1. A heat-resistant high-strength piston aluminum alloy, characterized in that: The heat-resistant high-strength piston aluminum alloy comprises an α-Al phase, a β-Si phase, an in-situ generated nano Ni-rich phase, a C-TiB2 seed and a B-TiC seed, wherein the C-TiB2 seed is a C-doped TiB2 seed, the B-TiC seed is a B-doped TiC seed, a portion of the C-TiB2 seed and the B-TiC seed are dispersedly distributed and used as nucleation cores of α-Al grains, the size of the nano Ni-rich phase is less than 500 nm, Wherein, based on 100wt% of the heat-resistant high-strength piston aluminum alloy, the content of Si is 10.5wt%-13.5wt%, and Among them, the heat-resistant high-strength piston aluminum alloy also includes Ni except the nano Ni-rich phase. Based on 100wt% of the heat-resistant high-strength piston aluminum alloy, the total content of Ni in the nano Ni-rich phase and Ni except the nano Ni-rich phase is 1.5wt%-2.8wt%.

2. The heat-resistant high-strength piston aluminum alloy according to claim 1, characterized in that: The nano Ni-rich phase further contains Cu element, and at least a portion of the nano Ni-rich phase is distributed between the β-Si phases.

3. The heat-resistant high-strength piston aluminum alloy according to claim 1, characterized in that: The C-TiB2 seed crystal and the B-TiC seed crystal are of submicron scale, and another part of the C-TiB2 seed crystal and the B-TiC seed crystal are in a linear cluster configuration and extend in three dimensions.

4. The heat-resistant high-strength piston aluminum alloy according to claim 1, characterized in that: Based on 100wt% of the heat-resistant and high-strength piston aluminum alloy, the total content of the C-TiB2 seed crystals and the B-TiC seed crystals is 0.01wt%-3.00wt%, based on 100wt% of the C-TiB2 seed crystals, the C doping amount is less than or equal to 2wt%, based on 100wt% of the B-TiC seed crystals, the B doping amount is less than or equal to 5wt%.

5. The heat-resistant high-strength piston aluminum alloy according to any one of claims 1 to 4, characterized in that: The heat-resistant and high-strength piston aluminum alloy also includes P and at least one of Cu, Mg, Zr, Fe, Mn, V, Mo, Cr, and Sc, wherein, based on 100wt% of the heat-resistant and high-strength piston aluminum alloy, the content of P is 0.01wt%-0.04wt%, the content of Cu is 1.5wt%-3.5wt%, the content of Mg is 0.5wt%-1.0wt%, the content of Zr is 0.10wt%-0.18wt%, the content of Fe is less than or equal to 1.0wt%, and the content of each single element of Mn, V, Mo, Cr and Sc is less than or equal to 0.2wt%.

6. A method for preparing a heat-resistant high-strength piston aluminum alloy according to any one of claims 1 to 5, characterized in that: The preparation method comprises: Prepare the first melt, add aluminum into the smelting furnace, heat and melt it to 750°C-800°C, then add silicon and completely dissolve the silicon; Prepare a second melt, add Al-TCB seed alloy to the first melt, and keep the temperature at 750° C.-800° C. for 1 min-10 min, wherein the Al-TCB seed alloy includes the C-TiB2 seed crystal and the B-TiC seed crystal; preparing a third melt, adjusting the temperature of the second melt to 820° C.-850° C., adding an Al-Ni alloy and dissolving it; The third melt is adjusted to 730° C.-780° C. and subjected to refining treatment, and then cast to obtain the heat-resistant high-strength piston aluminum alloy.

7. The preparation method according to claim 6, characterized in that: Based on 100wt% of the Al-TCB seed alloy, the total content of the C-TiB2 seed and the B-TiC seed is 0.5wt%-10.0wt%, and the addition amount of the Al-TCB seed alloy is 0.4wt%-30.0wt% of the total amount of the heat-resistant and high-strength piston aluminum alloy.

8. The preparation method according to claim 6, characterized in that: The step of preparing the third melt also includes: adding and dissolving the Al-Ni alloy at a temperature of 820°C-850°C, adding an Al-P seed alloy and adding and dissolving at least one of copper, Al-Fe alloy, Al-Mn alloy, Al-V alloy, Al-Mo alloy, Al-Cr alloy and Al-Sc alloy, and then adjusting the temperature to 750°C-760°C, adding and dissolving magnesium and an Al-Zr alloy.

9. The preparation method according to claim 6, characterized in that: The step of refining the third melt includes refining the third melt at 730° C.-780° C. for 15 min-30 min.

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