rus
Issue #1/2020
V. P. Biryukov, A. N. Prints, A. P. Savin, E. G. Gudushauri
Properties of Multicomponent Alloys Obtained by Additive Laser Technologies
Properties of Multicomponent Alloys Obtained by Additive Laser Technologies
DOI: 10.22184/1993-7296.FRos.2020.14.1.34.40
A review of the research of foreign studies on the characterization of high-entropy alloys (HEA) is given in this article. It has been shown that HEA based on a body-centered lattice (BCL) of a solid solution are more heat-resistant than a highly entropic alloy based on a face-centered lattice (FCL) of a solid solution. The results of the obtained quasi-high-entropy alloys (QHEA) with new properties instead of expensive highentropy alloys by introducing several serial powder materials based on iron, nickel, cobalt and tantalum nanocarbide additives to increase the wear resistance of coatings obtained by laser welding are presented. The introduction of 6% tantalum nanocarbide into the QHEA charge increases the wear resistance by 2.8 times compared to surfacing without carbide and increases the wear resistance by 7.2 times compared with the characteristic of the base material made of 40X steel. The technology of laser cladding QHEA can be used to restore various parts of machines, including those operating at elevated loads and temperatures. The characteristics of coatings obtained in the process of laser cladding are given. The range of variation of the operating parameters of the laser radiation is indicated: power of the displacement velocity, beam diameter.
A review of the research of foreign studies on the characterization of high-entropy alloys (HEA) is given in this article. It has been shown that HEA based on a body-centered lattice (BCL) of a solid solution are more heat-resistant than a highly entropic alloy based on a face-centered lattice (FCL) of a solid solution. The results of the obtained quasi-high-entropy alloys (QHEA) with new properties instead of expensive highentropy alloys by introducing several serial powder materials based on iron, nickel, cobalt and tantalum nanocarbide additives to increase the wear resistance of coatings obtained by laser welding are presented. The introduction of 6% tantalum nanocarbide into the QHEA charge increases the wear resistance by 2.8 times compared to surfacing without carbide and increases the wear resistance by 7.2 times compared with the characteristic of the base material made of 40X steel. The technology of laser cladding QHEA can be used to restore various parts of machines, including those operating at elevated loads and temperatures. The characteristics of coatings obtained in the process of laser cladding are given. The range of variation of the operating parameters of the laser radiation is indicated: power of the displacement velocity, beam diameter.
Теги: elastic modulus high-entropy alloys laser surfacing quasi-high-entropy alloys высокоэнтропийные сплавы квазивысокоэнтропийные сплавы лазерная наплавка модуль упругости
Properties of Multicomponent Alloys Obtained by Additive
Laser Technologies
V. P. Biryukov, A. N. Prints, A. P. Savin, E. G. Gudushauri
Federal budget - funded research Institute of Machines Science named after A.A.Blagonravov of the Russian Academy of Sciences, Moscow, Russia
A review of the research of foreign studies on the characterization of high-entropy alloys (HEA) is given in this article. It has been shown that HEA based on a body-centered lattice (BCL) of a solid solution are more heat-resistant than a highly entropic alloy based on a face-centered lattice (FCL) of a solid solution. The results of the obtained quasi-high-entropy alloys (QHEA) with new properties instead of expensive high-entropy alloys by introducing several serial powder materials based on iron, nickel, cobalt and tantalum nanocarbide additives to increase the wear resistance of coatings obtained by laser welding are presented. The introduction of 6% tantalum nanocarbide into the QHEA charge increases the wear resistance by 2.8 times compared to surfacing without carbide and increases the wear resistance by 7.2 times compared with the characteristic of the base material made of 40X steel. The technology of laser cladding QHEA can be used to restore various parts of machines, including those operating at elevated loads and temperatures.
The characteristics of coatings obtained in the process of laser cladding are given. The range of variation of the operating parameters of the laser radiation is indicated: power of the displacement velocity, beam diameter.
Keywords: high-entropy alloys, quasi-high-entropy alloys, elastic modulus, laser surfacing
Received: 15.11.2019
Accepted: 17.12.2019
Introduction
High-entropy alloys (HEA), also known as multicomponent alloys or alloys with several basic elements, were first obtained by casting [1, 2] in 2004. Wind farm – a completely new strategy for the design of the alloy, mixing a large number of elements or components. The content of each element is from 5 to 35 at.% [3]. High-entropy alloys based on a body-centered lattice (BCL) of a solid solution are more heat-resistant than a high-entropy alloy based on a face-centered lattice (FCL) of a solid solution. As compression tests showed, a highly entropic alloy based on bcc solid solution had a strength of 450 MPa at a temperature of 1300 °C [4]. A feature of highly entropic alloys is the ability to order the lattice parameter during annealing, which is accompanied by a decrease in the lattice parameter and a slight increase in the elastic modulus and hardness.
Powder mixtures of Fe, Co, Ni, Cr and Cu were obtained by mechanical mixing of chemically pure powders. The particle sizes of the powders were 50–120 μm [5]. Si (1.2%), Mn (1.2%), and Mo (2.8%) were used as additives. Laser surfacing was performed using a CO2 laser on a Q235 steel substrate. The powder mixture was preliminarily applied to the surface of the sample with a thickness of 1.7–2.0 mm. The processing was carried out with a radiation power of 2 kW, a beam diameter of 4.5 mm and a travel speed of 400 mm / min with overlapping tracks of 30%.
Heat treatment of deposited samples was carried out at temperatures of 550–950 °C for 5 hours. FeCoNiCrCu coatings with or without Si, Mn, and Mo additives were identified as a simple solid solution with a face-centered cubic lattice (FCL). The microhardness of the alloy without additives was 3750 MPa, which is approximately 50% higher than that of the same alloy obtained by the arc melting method. The introduction of Cu, Mn and Mo improves the quality of the coating and significantly increases the microhardness up to 4500 MPa.
The FeCoNiCrCu alloy has higher corrosion resistance in a 5% H2SO4 solution compared to the heat-resistant nickel alloy Ni60. Metal powders of Fe, Cr, Co, Si, Ti, Nb, Mo, and W with a purity of more than 99.6% and a size of about 150–250 μm were used to create a charge [6]. The powders were mixed in a specific proportion of 5:5:5:1:1:1:1:1 for 4 hours in a stainless steel vessel using a planetary ball mill. For surfacing, a YLS‑6000 IPG fiber laser was used. A powder with a thickness of 1.5 mm was placed on a substrate of W6Mo5Cr4V2 steel with dimensions of Ø50 × 10 mm. Laser surfacing was performed at a radiation power of 4 kW, a travel speed of 6 mm / s, and a spot diameter of 3.5 mm in argon. After surfacing, annealing was performed at a temperature of 800–1050 °C for 4 hours. The highest hardness of 10 500 MPa was achieved at an annealing temperature of 850 °C, which significantly exceeds the hardness of the sample after surfacing of 7800 MPa.
Powders of high-entropy Al2CrFeCoCuTiNix alloys (x = 0.0; 0.5; 1.0; 1.5; 2.0) were applied to a 0.8 mm thick Q235 steel substrate in the form of an organic binder based coating [7]. Laser surfacing was performed on the DL-HL-T5000B unit with a radiation power of 2500 W, a beam diameter of 4 mm, a beam moving speed of 3 mm / s, in an argon medium. The microhardness of the coatings increases with increasing nickel content and reaches a maximum value of 1102 HV, which is 4 times higher than the base material. Coating Al2CrFeCoCuTiNix alloys has good corrosion resistance in 1 mol / l NaOH solution and 3.5% NaCl solution. With an increase in the nickel content, corrosion resistance initially increases, but then begins to decline. The same thing happens with the wear resistance of the coating. Maximum wear resistance was obtained with a nickel content of 1.0%.
The aim of the work was to obtain quasi-high-energy alloys (QHEA) with new properties instead of expensive high-entropy alloys by introducing into the charge several serial powder materials based on iron, nickel, cobalt and tantalum nanocarbide additives to increase the wear resistance of coatings obtained by laser welding.
Equipment and research methods
In experimental studies, the IMASH RAS laser complex was used [8]. Samples were made of 40X steel with dimensions of 15 × 20 × 70 mm. Powders based on iron, nickel and cobalt of medium hardness in a ratio of 2:2:1, respectively, with a particle size of 40–150 μm, powder of tantalum nano-carbide with a particle size of 40–100 nm, were selected for the manufacture of the charge. The composition of the powders can be represented as (Ni-Cr-B-Si, Fe-Cr-Co-Mo, Co-Cr-W) TaСx (x = 0; 3.0; 4.0; 5.0; 6.0). Slurry coatings were applied with a thickness of 0.9–1.0 mm. An aqueous solution of hydroxyethyl cellulose was used as a binder material. By varying parameters, we chose the radiation power P = 800–1000 W, the processing speed V = 5–10 mm / s, and the beam diameter d = 2–3 mm. As an additional factor, scanning of a beam with a fixed frequency f = 215 Hz was considered. A resonance-type scanner with an elastic element on which a mirror is mounted was used. Metallographic studies of deposited coatings were carried out on a PMT‑3 microhardness tester with a load of 0.98 N, Altami MET 1C metallographic microscope (manufactured by Altami LLC, St. Petersburg) and AM413ML digital microscope (manufactured by AnMo Electronics Corporation, China). The structure and chemical composition of the deposited layers were studied using a TESCAN VEGA 3 SBH scanning electron microscope (manufactured by TESCAN, Czech Republic) with an energy dispersive analysis system using the modes of reflected and secondary electrons.
To determine the tribological characteristics of the deposited samples, an abrasion test was performed according to the Brinell-Haworth scheme [9]. Quartz sand with a particle size of 200–600 microns was fed into the friction zone, the test time was 10 minutes at a load of 15 N.
Results of experimental studies
Laser surfacing of the samples was carried out by a defocused beam and with transverse oscillations of the beam normal to the laser processing speed vector. Metallographic studies have established that surfacing at a minimum speed of 5 mm / s leads to a significant decrease in microhardness of both CVEC tracks and tracks with the addition of tantalum nano carbide. Therefore, the processing of samples for wear tests was carried out at the maximum possible velocity of the beam 8 mm / s. In this case, a uniform deposited bead and a minimum fusion zone of the sample base material of 5–15 μm were formed. Figure 1 (a and b) show microsections of deposited paths with a tantalum nanocarbide content of 6%, dimensions 0.85 × 2.3 mm, hardness 10200–10500 MPa, and 0.88 × 3.38 mm, hardness 10400–10900 MPa, obtained by defocused beam and beam scanning with a frequency of 215 Hz. The penetration zone of the base during processing with a defocused beam and a scanning beam was 280 and 110 μm, respectively. The cross-sectional area of a single deposited layer when scanning a beam is 1.53 times larger than when surfacing with a defocused beam. The dependence of the microhardness of the deposited coatings with transverse beam oscillations in height is shown in Fig. 2. With an increase in the content of tantalum nanocarbide in the mixture, the microhardness increases.
Fig. 3 shows the dependence of the wear of the samples on the content of tantalum nanocarbide. The loss of mass of the samples during the abrasion test decreases with increasing percentage of TaC powder in the deposited layers. Wear resistance – the reciprocal of the loss of mass of the sample. In this experiment, it increased by 7.2 times with the introduction of 6% TaC into the mixture compared with the base material of 40X steel and increased by 2.8 times compared to the QHEA surfacing.
Deposited coatings with QHEA and QHEA + TaC charge are not prone to crack formation. They have no defects such as pores and shells. Further research is required on the corrosion resistance of coatings. However, now we can assume a significant increase in corrosion resistance in comparison with commercially available powders based on iron and nickel.
QHEA laser cladding technology can be used to restore various parts of machines, including those operating at elevated loads and temperatures. The shafts of electric machines and gas pumping units, dies and punches of die tooling, both for cold and hot stamping, are subject to the greatest wear. In relation to them, this laser surfacing technology has been developed.
Conclusions
QHEA coverage is proposed. It has a microhardness of 4000–4500 MPa and can be used for surfacing various parts operating at elevated temperatures and pressures. The working parameters of the laser cladding technological process are determined: radiation power, speed of the laser beam, beam diameter.
The introduction of 6% tantalum nanocarbide into the QHEA charge increases the wear resistance by 2.8 times compared to surfacing without carbide and increases the wear resistance by 7.2 times compared with the characteristic of the base material made of 40X steel.
About authors
Biryukov Vladimir Pavlovich, Candidate of of Eng.Sc., laser 52@yandex.ru, FBFR Institute of Machines Science named after A.A.Blagonravov of the Russian Academy of Sciences,
http://www.imash.ru, Moscow, Russia.
ORCID: 0000-0002-3147-0844
Prints Anton Nikolaevich, FBFR Institute of Machines Science named after A.A.Blagonravov of the Russian Academy of Sciences,
http://www.imash.ru, Moscow, Russia.
ORCID ID: 0000-0001-6156-8810
Savin Alexander Petrovich, FBFR Institute of Machines Science named after A.A.Blagonravov of the Russian Academy of Sciences, http://www.imash.ru, Moscow, Russia.
Gudushauri Elguja Georgievich, Doc. of Eng.Sc., FBFR Institute of Machines Science named after A.A.Blagonravov of the Russian Academy of Sciences, http://www.imash.ru, Moscow, Russia.
Laser Technologies
V. P. Biryukov, A. N. Prints, A. P. Savin, E. G. Gudushauri
Federal budget - funded research Institute of Machines Science named after A.A.Blagonravov of the Russian Academy of Sciences, Moscow, Russia
A review of the research of foreign studies on the characterization of high-entropy alloys (HEA) is given in this article. It has been shown that HEA based on a body-centered lattice (BCL) of a solid solution are more heat-resistant than a highly entropic alloy based on a face-centered lattice (FCL) of a solid solution. The results of the obtained quasi-high-entropy alloys (QHEA) with new properties instead of expensive high-entropy alloys by introducing several serial powder materials based on iron, nickel, cobalt and tantalum nanocarbide additives to increase the wear resistance of coatings obtained by laser welding are presented. The introduction of 6% tantalum nanocarbide into the QHEA charge increases the wear resistance by 2.8 times compared to surfacing without carbide and increases the wear resistance by 7.2 times compared with the characteristic of the base material made of 40X steel. The technology of laser cladding QHEA can be used to restore various parts of machines, including those operating at elevated loads and temperatures.
The characteristics of coatings obtained in the process of laser cladding are given. The range of variation of the operating parameters of the laser radiation is indicated: power of the displacement velocity, beam diameter.
Keywords: high-entropy alloys, quasi-high-entropy alloys, elastic modulus, laser surfacing
Received: 15.11.2019
Accepted: 17.12.2019
Introduction
High-entropy alloys (HEA), also known as multicomponent alloys or alloys with several basic elements, were first obtained by casting [1, 2] in 2004. Wind farm – a completely new strategy for the design of the alloy, mixing a large number of elements or components. The content of each element is from 5 to 35 at.% [3]. High-entropy alloys based on a body-centered lattice (BCL) of a solid solution are more heat-resistant than a high-entropy alloy based on a face-centered lattice (FCL) of a solid solution. As compression tests showed, a highly entropic alloy based on bcc solid solution had a strength of 450 MPa at a temperature of 1300 °C [4]. A feature of highly entropic alloys is the ability to order the lattice parameter during annealing, which is accompanied by a decrease in the lattice parameter and a slight increase in the elastic modulus and hardness.
Powder mixtures of Fe, Co, Ni, Cr and Cu were obtained by mechanical mixing of chemically pure powders. The particle sizes of the powders were 50–120 μm [5]. Si (1.2%), Mn (1.2%), and Mo (2.8%) were used as additives. Laser surfacing was performed using a CO2 laser on a Q235 steel substrate. The powder mixture was preliminarily applied to the surface of the sample with a thickness of 1.7–2.0 mm. The processing was carried out with a radiation power of 2 kW, a beam diameter of 4.5 mm and a travel speed of 400 mm / min with overlapping tracks of 30%.
Heat treatment of deposited samples was carried out at temperatures of 550–950 °C for 5 hours. FeCoNiCrCu coatings with or without Si, Mn, and Mo additives were identified as a simple solid solution with a face-centered cubic lattice (FCL). The microhardness of the alloy without additives was 3750 MPa, which is approximately 50% higher than that of the same alloy obtained by the arc melting method. The introduction of Cu, Mn and Mo improves the quality of the coating and significantly increases the microhardness up to 4500 MPa.
The FeCoNiCrCu alloy has higher corrosion resistance in a 5% H2SO4 solution compared to the heat-resistant nickel alloy Ni60. Metal powders of Fe, Cr, Co, Si, Ti, Nb, Mo, and W with a purity of more than 99.6% and a size of about 150–250 μm were used to create a charge [6]. The powders were mixed in a specific proportion of 5:5:5:1:1:1:1:1 for 4 hours in a stainless steel vessel using a planetary ball mill. For surfacing, a YLS‑6000 IPG fiber laser was used. A powder with a thickness of 1.5 mm was placed on a substrate of W6Mo5Cr4V2 steel with dimensions of Ø50 × 10 mm. Laser surfacing was performed at a radiation power of 4 kW, a travel speed of 6 mm / s, and a spot diameter of 3.5 mm in argon. After surfacing, annealing was performed at a temperature of 800–1050 °C for 4 hours. The highest hardness of 10 500 MPa was achieved at an annealing temperature of 850 °C, which significantly exceeds the hardness of the sample after surfacing of 7800 MPa.
Powders of high-entropy Al2CrFeCoCuTiNix alloys (x = 0.0; 0.5; 1.0; 1.5; 2.0) were applied to a 0.8 mm thick Q235 steel substrate in the form of an organic binder based coating [7]. Laser surfacing was performed on the DL-HL-T5000B unit with a radiation power of 2500 W, a beam diameter of 4 mm, a beam moving speed of 3 mm / s, in an argon medium. The microhardness of the coatings increases with increasing nickel content and reaches a maximum value of 1102 HV, which is 4 times higher than the base material. Coating Al2CrFeCoCuTiNix alloys has good corrosion resistance in 1 mol / l NaOH solution and 3.5% NaCl solution. With an increase in the nickel content, corrosion resistance initially increases, but then begins to decline. The same thing happens with the wear resistance of the coating. Maximum wear resistance was obtained with a nickel content of 1.0%.
The aim of the work was to obtain quasi-high-energy alloys (QHEA) with new properties instead of expensive high-entropy alloys by introducing into the charge several serial powder materials based on iron, nickel, cobalt and tantalum nanocarbide additives to increase the wear resistance of coatings obtained by laser welding.
Equipment and research methods
In experimental studies, the IMASH RAS laser complex was used [8]. Samples were made of 40X steel with dimensions of 15 × 20 × 70 mm. Powders based on iron, nickel and cobalt of medium hardness in a ratio of 2:2:1, respectively, with a particle size of 40–150 μm, powder of tantalum nano-carbide with a particle size of 40–100 nm, were selected for the manufacture of the charge. The composition of the powders can be represented as (Ni-Cr-B-Si, Fe-Cr-Co-Mo, Co-Cr-W) TaСx (x = 0; 3.0; 4.0; 5.0; 6.0). Slurry coatings were applied with a thickness of 0.9–1.0 mm. An aqueous solution of hydroxyethyl cellulose was used as a binder material. By varying parameters, we chose the radiation power P = 800–1000 W, the processing speed V = 5–10 mm / s, and the beam diameter d = 2–3 mm. As an additional factor, scanning of a beam with a fixed frequency f = 215 Hz was considered. A resonance-type scanner with an elastic element on which a mirror is mounted was used. Metallographic studies of deposited coatings were carried out on a PMT‑3 microhardness tester with a load of 0.98 N, Altami MET 1C metallographic microscope (manufactured by Altami LLC, St. Petersburg) and AM413ML digital microscope (manufactured by AnMo Electronics Corporation, China). The structure and chemical composition of the deposited layers were studied using a TESCAN VEGA 3 SBH scanning electron microscope (manufactured by TESCAN, Czech Republic) with an energy dispersive analysis system using the modes of reflected and secondary electrons.
To determine the tribological characteristics of the deposited samples, an abrasion test was performed according to the Brinell-Haworth scheme [9]. Quartz sand with a particle size of 200–600 microns was fed into the friction zone, the test time was 10 minutes at a load of 15 N.
Results of experimental studies
Laser surfacing of the samples was carried out by a defocused beam and with transverse oscillations of the beam normal to the laser processing speed vector. Metallographic studies have established that surfacing at a minimum speed of 5 mm / s leads to a significant decrease in microhardness of both CVEC tracks and tracks with the addition of tantalum nano carbide. Therefore, the processing of samples for wear tests was carried out at the maximum possible velocity of the beam 8 mm / s. In this case, a uniform deposited bead and a minimum fusion zone of the sample base material of 5–15 μm were formed. Figure 1 (a and b) show microsections of deposited paths with a tantalum nanocarbide content of 6%, dimensions 0.85 × 2.3 mm, hardness 10200–10500 MPa, and 0.88 × 3.38 mm, hardness 10400–10900 MPa, obtained by defocused beam and beam scanning with a frequency of 215 Hz. The penetration zone of the base during processing with a defocused beam and a scanning beam was 280 and 110 μm, respectively. The cross-sectional area of a single deposited layer when scanning a beam is 1.53 times larger than when surfacing with a defocused beam. The dependence of the microhardness of the deposited coatings with transverse beam oscillations in height is shown in Fig. 2. With an increase in the content of tantalum nanocarbide in the mixture, the microhardness increases.
Fig. 3 shows the dependence of the wear of the samples on the content of tantalum nanocarbide. The loss of mass of the samples during the abrasion test decreases with increasing percentage of TaC powder in the deposited layers. Wear resistance – the reciprocal of the loss of mass of the sample. In this experiment, it increased by 7.2 times with the introduction of 6% TaC into the mixture compared with the base material of 40X steel and increased by 2.8 times compared to the QHEA surfacing.
Deposited coatings with QHEA and QHEA + TaC charge are not prone to crack formation. They have no defects such as pores and shells. Further research is required on the corrosion resistance of coatings. However, now we can assume a significant increase in corrosion resistance in comparison with commercially available powders based on iron and nickel.
QHEA laser cladding technology can be used to restore various parts of machines, including those operating at elevated loads and temperatures. The shafts of electric machines and gas pumping units, dies and punches of die tooling, both for cold and hot stamping, are subject to the greatest wear. In relation to them, this laser surfacing technology has been developed.
Conclusions
QHEA coverage is proposed. It has a microhardness of 4000–4500 MPa and can be used for surfacing various parts operating at elevated temperatures and pressures. The working parameters of the laser cladding technological process are determined: radiation power, speed of the laser beam, beam diameter.
The introduction of 6% tantalum nanocarbide into the QHEA charge increases the wear resistance by 2.8 times compared to surfacing without carbide and increases the wear resistance by 7.2 times compared with the characteristic of the base material made of 40X steel.
About authors
Biryukov Vladimir Pavlovich, Candidate of of Eng.Sc., laser 52@yandex.ru, FBFR Institute of Machines Science named after A.A.Blagonravov of the Russian Academy of Sciences,
http://www.imash.ru, Moscow, Russia.
ORCID: 0000-0002-3147-0844
Prints Anton Nikolaevich, FBFR Institute of Machines Science named after A.A.Blagonravov of the Russian Academy of Sciences,
http://www.imash.ru, Moscow, Russia.
ORCID ID: 0000-0001-6156-8810
Savin Alexander Petrovich, FBFR Institute of Machines Science named after A.A.Blagonravov of the Russian Academy of Sciences, http://www.imash.ru, Moscow, Russia.
Gudushauri Elguja Georgievich, Doc. of Eng.Sc., FBFR Institute of Machines Science named after A.A.Blagonravov of the Russian Academy of Sciences, http://www.imash.ru, Moscow, Russia.
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