Nanostructured gradient material based on Cu—Cr—W pseudo alloy prepared by high energy ball milling and spark plasma sintering

This study was conducted to obtain nanostructured mechanically activated composite particles from immiscible metals Cu, Cr and 5÷70 wt.% W, nanostructured bulk materials based on them and Cu / Cu—Cr—W nanostructured gradient material with different tungsten content by combined short-term (up to 150 min) high-energy ball milling (HEBM) and spark plasma sintering (SPS). Cu— Cr—W mechanically activated composites were obtained by HEBM of Cu + Cr + (5÷70 wt.%)W powder mixtures in the Activator-2S ball planetary mill at the rotating speed of 1388 rpm for the grinding chamber and 694 rpm for the planetary disk in an argon atmosphere for 150 min. Cu—Cr—W mechanically activated composite particles were consolidated by SPS in the temperature range of 800— 1000 °C at a pressure of 50 MPa for 10 min. The nanostructured gradient sintered material based on Cu—Cr—W pseudo alloys was pressed layer by layer in the following sequence (from pure copper to pseudo alloy with increasing tungsten content): Cu / Cu—Cr—5%W / Cu—Cr—15%W / Cu—Cr—70%W and sintered at 800 °C for 10 min. The crystal structure, microstructure, and properties of Cu— Cr—W mechanically activated composites and consolidated materials based on them were studied depending on production conditions. It was shown that the nanostructure formed in mechanically activated composites at the short-term HEBM stage (up to 150 min) was preserved for all Cu—Cr—W (5÷70 wt.% W) compounds after SPS. Based on SEM and EDX, refractory particles of W (d ~ 20÷100 nm) and Cr (d ~ 20÷50 nm) were uniformly distributed in the material volume (in the copper matrix). The hardness of Cu—Cr—W (15 wt.% W) bulk samples obtained from nanostructured powder mixtures (after 150 min HEBM) by SPS at 800 °C was approximately 6 times higher than the hardness of samples sintered from the mixture of starting components (without HEBM). For the Cu—Cr—70%W nanostructured compound (t_sps = 1000 °С) the hardness value was ~3 times higher than that for microcrystalline analogues. The highest re­lative density of 0.91 was achieved for Cu—Cr—15%W and Cu—Cr—70%W samples. Electrical resistivity for nanostructured Cu—Cr—W composites were 2 times higher than for microcrystalline samples. Apparently, this is due to an increase in grain boundaries and various defects accumulated in the material at the HEBM stage. The obtained results show that combined short-term HEBM and subsequent SPS is a promising way to produce nanocrystalline Cu—Cr—W composites and gradient materials based on them.

1. Myshkin N.K., Konchits V.V., Braunovich M. Electrical contacts. Dolgoprudnyy: Intellekt, 2008 (In Russ.).

2. Slade P. The vacuum interrupter contact. Components, Hybrids, and Manufacturing Technol., IEEE Trans. 1984. Vol. 7. No. 1. P. 25—32.

3. Avramov Yu.S., Shlyapin A.D. New composite materials based on immiscible components: Preparation, structure, properties. Moscow: MGIU, 1999 (In Russ.).

4. Yang Z., Zhang Q., Wang Q., Zhang Ch., Ding B. Vacuum arc characteristics on nanocrystalline Cu—Cr alloys. Vacuum. 2006. Vol. 81. P. 545—549.

5. Wei X., Yu D., Sun Z., Yang Z., Song X., Ding B. Arc characteristics and microstructure evolution of W—Cu contacts during the vacuum breakdown. Vacuum. 2014. Vol. 107. P. 83—89.

6. Shkodich N.F., Rogachev A.S., Vadchenko S.G., Moskovskikh D.O., Sachkova N.V., Rouvimov S., Mukasyan A.S. Bulk Cu—Cr nanocomposites by high-energy ball milling and spark plasma sintering. J. Alloys Compd. 2014. Vol. 617. P. 39—46.

7. Patra S., Gouthama, Mondal K. Densification behavior of mechanically milled Cu—8 at% Cr alloy and its mechanical and electrical properties. Progress in Natural Science: Materials International. 2014. Vol. 24. Iss. 6. P. 608—622.

8. Rogachev A.S., Kuskov K.V., Moskovskikh D.O., Usenko A.A., Orlov A.O., Shkodich N.F., Alymov M.I., Mukasyan A.S. Effect of mechanical activation on thermal and electrical conductivity of sintered Cu, Cr, and Cu/Cr composite pow-ders. Doklady Physics. 2016. Vol. 61. Iss. 6. P. 257—260.

9. Shkodich N.F., Rogachev A.S., Mukasyan A.S., Moskovs- kikh D.O., Kuskov K.V., Schukin A.S., Khomenko N.Yu. Preparation of copper—molybdenum nanocrystalline pseudoalloys using a combination of mechanical activation and spark plasma sintering. Tech. Russ. J. Phys. Chem. B. 2017. Vol. 11. No. 1. Р. 173—179.

10. Rogachev A.S., Kuskov K.V., Shkodich N.F., Moskovs- kikh D.O., Orlov A.O., Usenko A.A., Karpov A.V., Kovalev I.D., Mukasyan A.S. Influence of high-energy ball milling on electrical resistance of Cu and Cu/Cr nanocomposite materials produced by spark plasma sintering. J. Alloys Compd. 2016. Vol. 688. P. 468—474.

11. Lahiri I., Bhargava S. Compaction and sintering response of mechanically alloyed Cu—Cr powder. Powder Technol. 2009. Vol. 189. No. 3. P. 433—438.

12. Fang Q., Kang Z., Gan Y., Long Y. Microstructures and mechanical properties of spark plasma sintered Cu—Cr composites prepared by mechanical milling and alloying. Mater. Design. 2015. Vol. 88. P. 8—15.

13. Kumar A., Jayasankar K., Debata M., Mandal A. Mechanical alloying and properties of immiscible Cu—20 wt.% Mo alloy. J. Alloys Compd. 2015. Vol. 647. P. 1040—1047.

14. Wang D., Dong X., Zhou P., Sun A., Duan B. The sintering behavior of ultra-fine Mo—Cu composite powders and the sintering properties of the composite compacts. Int. J. Refract. Met. Hard Mater. 2014. Vol. 42. P. 240—245.

15. Zhanlei W., Huiping W., Zhonghua H., Hongyu X., Yifan L. Dynamic consolidation of W—Cu nano-alloy and Its performance as liner materials. Rare Met. Mater. Eng. 2014. Vol. 43. P. 1051—1055.

16. Fang Q., Kang Z. An investigation on morphology and structure of Cu—Cr alloy powders prepared by mechanical milling and alloying. Powder Technol. 2015. Vol. 270. Pt. A. P. 104—111.

17. Yang X., Zou J., Xiao P., Wang X. Effects of Zr addition on properties and vacuum arc characteristics of Cu—W alloy. Vacuum. 2014. Vol. 106. P. 16—20.

18. Wei X., Yu D., Sun Z., Yang Z., Song X., Ding B. Effect of Ni addition on the dielectric strength and liquid phase separation of Cu—Cr alloys during the vacuum breakdown. Vacuum. 2014. Vol. 109. P. 162—165.

19. Weichan C., Shuhua L., Xiao Z., Xianhui W., Xiaohong Y. Effect of Mo addition on microstructure and vacuum arc characteristics of CuCr50 alloy. Vacuum. 2011. Vol. 85. P. 943—948.

20. Sheibani S., Heshmati-Manesh S., Ataie A. Influence of Al2O3 nanoparticles on solubility extension of Cr in Cu by mechanical alloying. Acta Mater. 2010. Vol. 58. P. 6828— 6834.

21. Sauvage X., Jessner P., Vurpillot F., Rippan R. Nanostructure and properties of a Cu—Cr composite processed by severe plastic deformation. Scripta Mater. 2008. Vol. 58. P. 1125—1128.

22. Kumar A., Kumar Pradhan S., Jayasankar K., Debata M., Kumar Sharma R., Mandal A. Structural investigations of nanocrystalline Cu—Cr—Mo alloy prepared by high- energy ball milling. J. Electr. Mater. 2017. Vol. 46. Iss. 2. P. 1339—1347.

23. Mula S., Panigrahi J., Kang P.C., Koch C.C. Effect of microwave sintering over vacuum and conventional sintering of Cu based nanocomposites. J. Alloys Compd. 2014. Vol. 588. P. 710—715.

24. Sheibani S., Heshmati-Manesh S., Ataie A., Caballero A., Criado J.M. Spinodal decomposition and precipitation in Cu—Cr nanocomposite. J. Alloys Compd. 2014. Vol. 587. P. 670—676.

25. Paris S., Gaffet E., Bernard F., Munir Z.A. Spark plasma synthesis from mechanically activated powders: A versatile route for producing dense nanostructured iron aluminides. Scripta Mater. 2004. Vol. 50. P. 691—696.

26. Xian-liang Zhou, Ying-hu Dong, Xiao-zhen Hua, Rafi-uddin, Zhi-guoYe. Effect of Fe on the sintering ad thermal properties of Mo—Cu composites. Mater. Des. 2010. Vol. 31. P. 1603—1606.