Metal Powders for Additive Manufacturing

Abstract

The present invention relates to a metal powder having a composition comprising the following elements: 12%≦Mo≦18%, 3%≦P≦7%, 0.5%≦C≦3%, 0.5%≦B≦5%, Si≦1%, the remainder being Fe and unavoidable impurities resulting from manufacturing, the microstructure of the metal powder comprising at least 95% by weight of amorphous phase and the remainder being made up of crystalline phase.

Description

[Technical Field]

[0001] The present invention relates to a metal powder for the production of steel parts, in particular for their additive manufacturing. The present invention also relates to a method for producing said metal powder. [Background technology]

[0002] Fe-based bulk metallic glasses (BMGs) have attracted attention due to their excellent soft magnetic properties, high corrosion resistance, good mechanical properties, and high wear resistance. They have been particularly utilized in the electrical and electronics industries as highly efficient magnetic medium and high-frequency transformers. However, to date, most Fe-based BMGs with good soft magnetic properties can only be produced using highly complex process conditions. Their liquid compositions must be formed between chill rolls at high cooling rates to obtain amorphous materials, typically in the form of thin ribbons. Apart from this complex process, this production in thin ribbons significantly limits their use. Summary of the Invention [Problem to be solved by the invention]

[0003] It is therefore an object of the present invention to ameliorate the shortcomings of the prior art by providing an Fe-based BMG that can be easily produced and easily processed to obtain a final part. [Means for solving the problem]

[0004] To this end, a first object of the present invention is to provide a metal powder containing the following elements, expressed in weight content: 12%≦Mo≦18% 3%≦P≦7% 0.5%≦C≦3% 0.5%≦B≦5% Si≦1% with the remainder being Fe and unavoidable impurities resulting from manufacturing, and the microstructure of the metal powder comprises at least 95% by weight of an amorphous phase, with the remainder being made up of a crystalline phase.

[0005] The metal powder according to the present invention may also have any of the characteristics listed below, considered individually or in combination. - Mo content is 13-16.5 wt%; - the P content is 6 to 7% by weight; - the B content is 0.7 to 2% by weight; - the Si content is 0.3 to 0.6 wt%; - the microstructure of the metal powder comprises at least 99% by weight of an amorphous phase; - the average particle size is 1 to 150 μm; - the average particle size is 1 to 20 μm; - the average particle size is 20-63 μm; - The average particle size is 60-150 μm.

[0006] A second object of the present invention is a method for producing metal powder for additive manufacturing, comprising: a) melting elements and / or metal alloys at a temperature of at least 100°C above the liquidus temperature to obtain the following elements, expressed in weight content: 12%≦Mo≦18% 3%≦P≦7% 0.5%≦C≦3% 0.5%≦B≦5% Si≦1% obtaining a molten composition comprising the remainder Fe and unavoidable impurities resulting from the production, b) spraying the molten composition through a nozzle using a gas pressurized to 10-30 bar, The method comprises:

[0007] A third object of the invention consists of a method for producing printed parts by additive manufacturing, in which a powder according to the invention or a powder obtained by a method according to the invention is printed by laser powder bed fusion.

[0008] The method for producing the printed part may also have any of the features listed below, considered individually or in combination. - further comprising a first step of forming a powder layer having a thickness of less than 100 μm, and a second step of forming a shaped layer by using a focused laser beam to melt at least a portion of the powder layer in an atmosphere consisting essentially of an inert gas; - Laser power is limited to a maximum of 120W, - Scanning speed is 400~750mm / sec. - Linear energy density is 80~200J / m, - The hatch spacing is 40-100 μm, - Volumetric energy density is 80~200J / mm 3 is.

[0009] A fourth object of the present invention consists in a printed part obtained from a powder according to the invention or obtained by a method according to the invention, the microstructure of which comprises at least 75% by weight of an amorphous phase, the remainder being made up of crystalline phase(s). DETAILED DESCRIPTION OF THE INVENTION

[0010] The invention will be better understood on reading the following description, which is given purely for illustrative purposes and is not intended to be limiting.

[0011] Molybdenum is present in the composition according to the invention in a content of 12 to 18% by weight. Molybdenum is an element that promotes the glass-forming ability of steels by promoting a disruptive effect. Below 12% by weight, the glass-forming ability is insufficient. Above 18% by weight, molybdenum can segregate during solidification, which will promote the nucleation of Mo-rich phases that are detrimental to the glass-forming ability.

[0012] Preferably, the Mo content is between 13 and 16.5 wt % to further improve the glass forming ability.

[0013] The phosphorus content is between 3 and 7% by weight. Phosphorus is another element that promotes the glass-forming ability of steel. Below 3% by weight, the glass-forming ability is not sufficient. Above 7% by weight, phosphorus forms brittle phases that can cause hot cracking, which is detrimental to the integrity of the material. Phosphorus also increases the crystallinity of the material.

[0014] Preferably, the P content is between 6 and 7 wt % in order to further enhance the glass forming ability.

[0015] The carbon content is between 0.5 and 3% by weight. Carbon is another element that promotes the glass-forming ability of steel by promoting the disruptive effect. It has a high negative enthalpy of mixing with Fe, and its atomic radius is 89 pm smaller than that of Fe. However, a high carbon content can lead to the formation of carbides, especially cementite, M6C-carbides, and KSI-carbides, which initiate nucleation. This is detrimental to the microstructure.

[0016] Preferably, the C content is comprised between 1.4 and 2.2% by weight in order to further improve the glass-forming ability of the steel and to retard crystallization.

[0017] The boron content is between 0.5 and 5% by weight. Boron significantly increases the hardness and wear resistance of the material. Boron is also used for grain refinement and to increase the glass-forming ability (GFA) of steel, and its atomic radius is 69 pm smaller than that of Fe. For these reasons, the B content is at least 0.5% by weight. However, the B content is limited to 5% by weight, because above this value, the formation of borides is promoted, which induces embrittlement in the material.

[0018] Preferably, to further avoid brittleness, the B content is comprised between 0.7 and 2% by weight.

[0019] Silicon is present in the composition according to the invention in a content of up to 1% by weight. Si lowers the liquidus temperature, thus minimizing the risk of crystallization above the glass transition temperature. Silicon also promotes a disruption effect, since it tends to form complex phases at equilibrium. However, above 1% by weight, Si tends to increase the liquidus temperature (which increases the risk of crystallization) and to form Si-rich carbides, such as (Fe)2(Mo)2(FeMoSi)2(C)1, which initiate nucleation. Preferably, the Si content is between 0.3 and 0.6% by weight.

[0020] The remainder is made up of iron and unavoidable impurities resulting from manufacturing. Nickel, chromium, manganese, titanium, rare earths, sulfur, nitrogen, oxygen, aluminum, vanadium, and copper are the main impurities. They are not intentionally added. They may be present in the iron alloy used as raw material and / or in the pure elements. Nitrogen can also be introduced during atomization. Their content is preferably controlled to avoid deleterious microstructural changes and / or to avoid crystallization. Therefore, the content of Ni should be limited to 2% by weight, the content of Cr to 1% by weight, the content of Mn to 1% by weight, Ti to 0.5% by weight, rare earths to 1% by weight, and the content of other impurities to 0.03% by weight.

[0021] The metal powder has a microstructure comprising at least 95% by weight of an amorphous phase, with the remainder being made up of crystalline phase(s). The crystalline phase(s) can be at least one of austenite, ferrite, cementite, M2B-type borides such as (FeMoMn)2(B)1, M3B2-type borides such as (FeMo)0.4(Fe)0.2(B)0.4, M2P-type phosphides such as (FeMoMn)2(PSi)1, M3P-type phosphides such as (FeMO)3(P)1, M6C-type carbides such as (Fe)2(Mo)2(FeMoSi)2(C)1, and KSI-type carbides such as (FeMO)3(C)1. Preferably, the microstructure comprises at least 99% by weight of an amorphous phase, with the remainder being made up of crystalline phase(s). More preferably, the microstructure is completely amorphous. The weight fraction of the amorphous phase can be calculated by Rietveld analysis of powder X-ray diffraction (XRD) measurements.

[0022] The powder preferably has a high sphericity or form factor. The form factor is defined as 4πA / P in accordance with ISO 9276-6:2008. 2 The average form factor is defined as, where A is the measured area covered by the particle projection and P is the measured perimeter / perimeter of the particle projection. A value of 1.0 indicates a perfect sphere. The average form factor of the powder is preferably at least 0.70, more preferably at least 0.80. This high form factor makes the metal powder highly flowable. This results in easier additive manufacturing and denser, harder printed parts. The average form factor can be measured by dynamic image analysis according to ISO 13322-2:2021. In particular, the average form factor can be measured with a Digital Imaging Particle Size and Shape Analyzer such as the Camsizer®.

[0023] Preferably, no more than 7% of the particles have a form factor of less than 0.65.

[0024] In addition to form factor, aspect ratio can be used to classify powder particles. Aspect ratio is defined in ISO 9276-6:2008 as the ratio between the minimum length of the ferret and the maximum length of the ferret. Aspect ratio can be measured by dynamic image analysis according to ISO 13322-2:2021. Aspect ratios can be measured, inter alia, with a Digital Imaging Particle Size and Shape Analyzer such as Camsizer®. The average aspect ratio should preferably be greater than 0.7, more preferably greater than 0.75.

[0025] The particle size distribution, measured by laser diffraction according to ISO 13320:2020, preferably meets the following requirements (in μm): 5≦D10≦25 35≦D50≦85 100≦D90≦280

[0026] The powder can be obtained by first mixing and melting pure elements and / or iron alloys as raw materials. The powder can also be obtained by using pre-alloyed ingots of the required composition.

[0027] Pure elements are usually preferred to avoid having excessive impurities from the iron alloy, which may facilitate crystallization. Nevertheless, in the present case, it has been observed that impurities from the iron alloy are not detrimental to achieving an amorphous phase.

[0028] Iron alloys refer to various alloys of iron containing a high proportion of one or more other elements, such as molybdenum, phosphorus, boron, or silicon. The main alloys are FeMo (usually containing 60–75 wt% Mo), FeP (usually containing 15–30 wt% P), FeB (usually containing 17.5–20 wt% B), FeSi (usually containing 15–90 wt% Si), FeNi (usually containing 70–95 wt% Ni), FeCr (usually containing 50–70 wt% Cr), FeMn (usually containing 70–80 wt% Mn), FeTi (usually containing 45–75 wt% Ti), FeAl (usually containing 40–60 wt% Al), and FeV (usually containing 35–85 wt% V).

[0029] Alternatively, the raw materials can be added as pure elements (usually greater than 99% by weight) which can be carbon and pure metals such as iron, molybdenum, boron, silicon, nickel, chromium, manganese, titanium, rare earths, aluminum, vanadium, copper, among others.

[0030] Those skilled in the art know how to mix different iron alloys and pure elements to obtain a target composition.

[0031] Preferably, the mixture comprises FeMo iron alloy, FeP iron alloy, FeB iron alloy, FeSi iron alloy, graphite and Fe.

[0032] Once the composition is obtained by mixing the pure elements and / or iron alloys in the appropriate proportions, the composition is heated to a temperature at least 100°C above its liquidus temperature and maintained at this temperature to melt all the ingredients and homogenize the melt. Due to this heating, the viscosity of the molten composition is reduced, which helps to obtain a powder with high satellite-free sphericity and a suitable particle size distribution. However, since surface tension increases with temperature, it is preferable not to heat the composition more than 530°C above its liquidus temperature.

[0033] Preferably, the composition is heated to a temperature at least 200°C above its liquidus temperature to promote the formation of highly spherical particles, and more preferably, the composition is heated to a temperature between 220 and 280°C above its liquidus temperature.

[0034] In one variant of the invention, the composition is heated between 1300 and 1600° C., which represents a good compromise between viscosity reduction and surface tension increase.

[0035] The molten composition is then atomized into fine metal droplets by forcing the molten metal stream through an orifice, a nozzle, under moderate pressure and impinging upon it with a jet of gas (gas atomization) or a jet of water (water atomization). In gas atomization, gas is introduced into the metal stream just before it exits the nozzle, and serves to create turbulence as the entrained gas expands (by heating) and exits into a large collection volume, the spray tower. The latter is filled with gas to promote further turbulence in the molten metal jet. The metal droplets cool as they fall within the spray tower. Gas atomization is preferred because it favors the production of powder particles with a high degree of roundness and a small number of satellites.

[0036] The atomizing gas is preferably argon or nitrogen, or a mixture thereof. Both of these increase the melt viscosity more slowly than other gases, such as helium, which promotes the formation of smaller particle sizes. They also control the purity of the chemicals, avoid undesirable impurities, and play a role in the morphology of the powder. Since the molar weight of nitrogen is 14.01 g / mol compared to 39.95 g / mol for argon, finer particles can usually be obtained using argon rather than nitrogen. Meanwhile, the specific heat capacity of nitrogen is 1.04 J / (gK) compared to 0.52 for argon. Therefore, nitrogen increases the cooling rate of the particles. To avoid contamination of the composition with nitrogen, argon may be preferred over nitrogen.

[0037] The gas pressure directly affects the particle size distribution. Also, the higher the pressure, the faster the cooling rate. Therefore, high pressure prevents the particles from crystallizing. Therefore, the gas pressure is set between 10 and 30 bar to optimize the particle size distribution and promote the formation of an amorphous phase. Preferably, the gas pressure is set between 14 and 20 bar to promote the formation of particles whose size is most compatible with additive manufacturing techniques.

[0038] The nozzle diameter affects the flow rate of the molten metal, and therefore the particle size distribution and cooling rate. The maximum nozzle diameter is limited to 4 mm to limit the increase in average particle size and the decrease in cooling rate. The nozzle diameter is preferably between 2 and 3 mm to more precisely control the particle size distribution.

[0039] The gas to metal ratio, defined as the ratio between gas flow rate (Kg / hr) and metal flow rate (Kg / hr), is preferably maintained between 1.5 and 7, more preferably between 3 and 4. This helps to adjust the cooling rate.

[0040] According to one variant of the invention, in the case of moisture absorption, the metal powder obtained by atomization is dried to further improve its flowability, the drying being preferably carried out at 100° C. in a vacuum chamber.

[0041] The metal powder obtained by atomization can either be used as is or can be sieved to retain particles of a size better suited to the additive manufacturing technique to be used subsequently. For example, for additive manufacturing by powder bed fusion, the range of 20 to 63 μm (called fraction F2) is preferred, with the range of 20 to 40 μm being even more preferred. For additive manufacturing by laser metal deposition or direct metal deposition, the range of 60 to 150 μm (called F3) is preferred, with the range of 40 to 125 μm being even more preferred. Fraction F1, which covers particle sizes below 20 μm, can be used, for example, in binder jetting.

[0042] Parts made from the metal powder according to the invention can be obtained by additive manufacturing techniques such as laser powder bed fusion (LPBF), direct metal laser sintering (DMLS), electron beam melting (EBM), selective thermal sintering (SHS), selective laser sintering (SLS), laser metal deposition (LMD), direct metal deposition (DMD), direct metal laser melting (DMLM), direct metal printing (DMP), laser cladding (LC), binder jetting (BJ), etc. Coatings made with the metal powder according to the invention can also be obtained by manufacturing techniques such as cold spray, thermal spray, high velocity oxy-fuel, etc.

[0043] Specifically, the present invention utilizes the LPBF process, an additive manufacturing technology. Using a coating mechanism, thin layers of metal powder are evenly distributed onto a substrate platform, usually metal, fixed to an index table that moves in a vertical axis. This occurs in a chamber containing a tightly controlled atmosphere. As each layer is distributed, each 2D slice of the part shape is fused by selectively melting the powder. This is achieved using a high-power laser beam, usually an ytterbium fiber laser. The laser energy is strong enough to allow complete melting (welding) of particles in the form of tracks or strips. Essentially, once a track is formed, the process is repeated with the next track, separated from the first by a hatch spacing. This process is repeated layer by layer until the part is complete. The overhanging shape is supported by unmelted powder from the previous layer. The main process parameters used in LPBF are typically layer thickness, hatch spacing, scanning speed, and laser power. After the process is complete, the remaining powder is sieved and reused.

[0044] The method for producing an additively manufactured part by LPBF includes a first step of forming a powder layer with a powder according to the present invention. Preferably, the powder layer is less than 100 μm thick. Above 100 μm, the laser may not melt the powder at all layer thicknesses, which may lead to porosity in the part. Preferably, the layer thickness is kept between 10 and 60 μm to optimize powder melting.

[0045] In a second step, a focused laser beam forms a shaped layer by melting at least a portion of the powder layer under process conditions detailed below.

[0046] With LPBF, each layer of the printed part is at least partially melted in an atmosphere consisting essentially of an inert gas.

[0047] The laser power is preferably limited to a maximum of 120 W. Preferably, the laser power is set above 50 W to facilitate melting at all layer thicknesses. In a preferred embodiment, the laser power is between 55 and 115 W.

[0048] The scanning speed is preferably 400-750 mm / s, more preferably 450-700 mm / s. Below 400 mm / s, excessive energy provided by the laser can lead to keyhole porosity and / or spatter, which, if not properly dragged outside the powder bed, can accumulate on the powder layer and create voids in the printed part. Above 750 mm / s, the energy provided by the laser to the powder may not be sufficient to melt the powder at all layer thicknesses.

[0049] The linear energy density (LED) is preferably between 80 and 200 J / m. LED is defined as the ratio between the laser power and the scanning speed expressed in m / s. Below 80 J / m, the LED may not be sufficient to properly print the part (due to keyhole). Above 200 J / m, the excessive energy provided by the laser may result in spatter depositing on the powder layer if not properly dragged outside the powder bed. Such deposits create voids within the printed part.

[0050] The hatch spacing is preferably 40 to 100 μm. If it is less than 40 μm, each point on the printed part may be remelted multiple times, which may lead to overheating. If it is more than 100 μm, unmelted powder may be trapped between two tracks. More preferably, the hatch spacing is 50 to 80 μm.

[0051] The volumetric energy density (VED) is preferably 80 to 200 J / mm 3 VED is defined as P / (v·h·lt), where P is the laser power, v is the scanning speed, h is the hatch spacing, and lt is the powder layer thickness. More preferably, VED is 90 to 160 J / mm 3 is.

[0052] The laser spot size is preferably comprised between 30 and 150 μm.

[0053] Parts made from metal powders according to the present invention by additive manufacturing techniques have specific properties and characteristics.

[0054] These microstructures comprise at least 75 wt. % amorphous phase, with the remainder made up of crystalline phase(s). The crystalline phase(s) may be at least one of austenite, ferrite, cementite, M2B-type borides such as (FeMoMn)2(B)1, M3B2-type borides such as (FeMo)o.4(Fe)o.2(B)o.4, M2P-type phosphides such as (FeMoMn)2(PSi)1, M3P-type phosphides such as (FeMO)3(P)1, M6C-type carbides such as (Fe)2(Mo)2(FeMoSi)2(C)1, and KSI-type carbides such as (FeMO)3(C)1. The microstructures preferably comprise at least 80 wt. %, more preferably at least 95 wt. % amorphous phase, with the remainder made up of crystalline phase(s).

[0055] The parts are very hard, with a Vickers hardness of over 780 Hv1. [Example]

[0056] The following examples and tests presented below are non-limiting in nature and should be considered for illustrative purposes only: they illustrate the advantageous features of the present invention and the importance of the parameters selected by the inventors after extensive experimentation further establish the properties that can be achieved with metal powders according to the present invention.

[0057] <Powder 1> A metal composition containing 16.11 wt% Mo, 6.23 wt% P, 1.464 wt% C, 0.8 wt% B, 0.47 wt% Si, <0.25 wt% Mn, <0.3 wt% Ti, <0.01 wt% Al, <0.001 wt% Cr, <0.2 wt% V, 0.019 wt% O, 0.0076 wt% S, 5.9 ppm N, and the remainder being iron, was obtained by first mixing and melting the following iron alloy and pure elements in the following proportions: 23.83 wt.% FeP containing 73.61 wt.% Fe, 25.93 wt.% P, 1.55 wt.% Si, 1.5 wt.% Ti, <0.7 wt.% Mn, <0.4 wt.% Cr, <0.7 wt.% V, 6.04 wt.% FeB containing 82.33 wt.% Fe, 18.16 wt.% B, 0.13 wt.% Al, 0.007 wt.% S, 0.31 wt.% C, 0.03 wt.% P and 0.54 wt.% Si, 14.49 wt.% Mo, 2.37% by weight of graphite, - 53.26 wt% iron ingot containing 99.79 wt% Fe, 0.005 wt% C, 0.001 wt% Al, 0.15 wt% Mn, 0.002 wt% Si, 0.002 wt% P, 0.002 wt% S.

[0058] The metal composition was heated to 1315°C, ie, 250°C above the liquidus temperature, and then gas atomized with argon under the following process conditions: - Gas pressure: 16 bar, - Nozzle diameter: 2.5mm - Gas to Metal Ratio: 3.21

[0059] The resulting metal powder was then dried under vacuum at 100°C for 0.5 to 1 day.

[0060] The powder was then sieved and classified into fractions F1 to F3. Its flowability, sphericity and roundness were evaluated and found to be satisfactory for additive manufacturing applications.

[0061] The metal powder had the following properties:

[0062] XRD and electron backscatter diffraction (EBDS) showed no evidence of any crystalline phases, therefore the microstructure was at least 99 wt% amorphous.

[0063] The average form factor, measured by dynamic image analysis according to ISO 13322-2:2021 using a Camsizer® instrument, was 0.87 for fraction F2.

[0064] The particle size distribution measured by laser diffraction according to ISO 13320:2020 exhibited the following characteristics: D10=15.64 μm, D50=52.06 μm and D90=137.15 μm.

[0065] Thanks to these features, the resulting metal powder exhibited the following magnetic properties measured by a vibrating sample magnetometer (VSM): coercivity Hc measured at room temperature of 8×10 -5 T. The magnetic saturation Ms measured at room temperature was 70.6 Am 2 / kg. The residual magnetization measured at room temperature was 0.043 Am 2 / kg.

[0066] <Powder 2> A metal composition containing 14.2 wt% Mo, 6.53 wt% P, 1.94 wt% C, 1.02 wt% B, 0.43 wt% Si, 0.77 wt% Mn, <0.01 wt% Al, 0.11 wt% Cr, 0.09 wt% Ni, <0.1 wt% Cu, 0.019 wt% O, 0.012 wt% S, <20 ppm N, with the balance being iron, was obtained by first mixing and melting the following iron alloy and pure elements in the following proportions: 21.41 wt% FeMo containing 32.3 wt% Fe, 0.09 wt% C, 0.45 wt% Cu, 66.86 wt% Mo, 0.04 wt% P, 0.04 wt% S, 0.29 wt% Si, 24.37 wt.% FeP containing 73.61 wt.% Fe, 25.93 wt.% P, 1.55 wt.% Si, 1.5 wt.% Ti, <0.7 wt.% Mn, <0.4 wt.% Cr, <0.7 wt.% V, 6.17 wt.% FeB containing 82.33 wt.% Fe, 18.16 wt.% B, 0.13 wt.% Al, 0.007 wt.% S, 0.31 wt.% C, 0.03 wt.% P and 0.54 wt.% Si, 0.1 wt% FeSi containing 23.51 wt% Fe, 0.82 wt% Al, 0.09 wt% C, 0.018 wt% P, 0.002 wt% S, 75.56 wt% Si, 2.38% by weight of graphite, - 45.57 wt% iron ingot containing 99.79 wt% Fe, 0.005 wt% C, 0.001 wt% Al, 0.15 wt% Mn, 0.002 wt% Si, 0.002 wt% P, 0.002 wt% S.

[0067] The metal composition was heated to 1580°C, ie, 515°C above the liquidus temperature, and then gas atomized with argon under the following process conditions: - Gas pressure: 16 bar - Nozzle diameter: 3mm - Gas to Metal Ratio: 1.79

[0068] The resulting metal powder was then dried under vacuum at 100°C for 0.5 to 1 day.

[0069] The powder was then sieved and classified into fractions F1 to F3. Its flowability, sphericity and roundness were evaluated and found to be satisfactory for additive manufacturing applications.

[0070] The metal powder had the following properties:

[0071] XRD and electron backscatter diffraction (EBDS) showed no evidence of any crystalline phases, therefore the microstructure was at least 99 wt% amorphous.

[0072] The average form factor, measured by dynamic image analysis according to ISO 13322-2:2021 using a Camsizer® instrument, was 0.71 for fraction F2.

[0073] The particle size distribution measured by laser diffraction according to ISO 13320:2020 showed the following characteristics: D10=15.7 μm, D50=72.1 μm and D90=247.2 μm.

[0074] <Printing test> Fraction F2 of powders 1 and 2 was then used to fabricate a 1 cm layer by laser powder bed fusion using a layer thickness of 20 μm and a laser spot size of 55 μm. 3 A cube was printed.

[0075] The cubes were then evaluated, and the corresponding results are summarized in Table 1 below. The weight fraction of the amorphous phase was calculated by Rietveld refinement of powder X-ray diffraction (XRD) measurements using TOPAS software from Bruker. All printed parts according to the invention had a microstructure containing 80-90% by weight of amorphous phase, with the remainder made up of crystalline phases, including austenite. No segregation or hot cracking was observed.

[0076] [Table 1]

Claims

1. Metal powders containing the following elements expressed in weight percentages: 12%≦Mo≦18% 3%≦P≦7% 0.5%≦C≦3% 0.5%≦B≦5% Si≦1% with the remainder being Fe and unavoidable impurities resulting from manufacturing, wherein the microstructure of the metal powder comprises at least 95% by weight of an amorphous phase and the remainder is made up of a crystalline phase.

2. 2. The metal powder according to claim 1, wherein the Mo content is 13 to 16.5 wt. %.

3. 3. The metal powder according to claim 1, wherein the P content is 6 to 7% by weight.

4. The metal powder according to any one of claims 1 to 3, wherein the B content is 0.7 to 2 wt%.

5. The metal powder according to any one of claims 1 to 4, wherein the Si content is 0.3 to 0.6 wt%.

6. 6. The metal powder according to claim 1, wherein the microstructure of the metal powder comprises at least 99% by weight of an amorphous phase.

7. The metal powder according to any one of claims 1 to 6, having an average particle size of 1 to 150 µm.

8. The metal powder according to claim 7, having an average particle size of 1 to 20 μm.

9. The metal powder according to claim 7, having an average particle size of 20 to 63 μm.

10. The metal powder according to claim 7, having an average particle size of 60 to 150 μm.

11. 1. A method of producing metal powder for additive manufacturing, comprising: a) by melting elements and / or metal alloys at a temperature of at least 100° C. above the liquidus temperature to obtain the following elements, expressed in weight content: 12%≦Mo≦18% 3%≦P≦7% 0.5%≦C≦3% 0.5%≦B≦5% Si≦1% obtaining a molten composition comprising the remainder Fe and unavoidable impurities resulting from production, b) atomizing the molten composition through a nozzle using gas pressurized to 10-30 bar; A method comprising:

12. 12. A method for producing a printed part by additive manufacturing, wherein a powder according to any one of claims 1 to 10 or a powder obtained according to claim 11 is printed by laser powder bed fusion.

13. 13. The method of claim 12, comprising a first step of forming a powder layer having a thickness of less than 100 μm, and a second step of forming a shaped layer by a focused laser beam by melting at least a portion of the powder layer in an atmosphere consisting essentially of an inert gas.

14. - Laser power is limited to a maximum of 120W; - the scanning speed is between 400 and 750 mm / s; - a linear energy density of 80 to 200 J / m; - the hatch spacing is between 40 and 100 μm; - Volumetric energy density of 80 to 200 J / mm ３ That is, 14. The method according to claim 12 or 13.

15. 15. A printed part obtainable from the powder according to any one of claims 1 to 10 or by the method according to any one of claims 12 to 14, wherein the microstructure of the printed part comprises at least 75% by weight of an amorphous phase, the remainder being made up of a crystalline phase.

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