Microstructures and properties of Al₂O₃ dispersion-strengthened copper alloys prepared through different methods

Abstract

Al₂O₃ dispersion copper alloy powder was prepared by internal oxidation, and three consolidation methods—high-velocity compaction (HVC), hot pressing (HP), and hot extrusion (HE)—were used to prepare Al₂O₃ dispersion-strengthened copper (Cu–Al₂O₃) alloys. The microstructures and properties of these alloys were investigated and compared. The results show that the alloys prepared by the HP and HE methods exhibited the coarsest and finest grain sizes, respectively. The alloy prepared by the HVC method exhibited the lowest relative density (98.3% vs. 99.5% for HP and 100% for HE), which resulted in the lowest electrical conductivity (81% IACS vs. 86% IACS for HP and 87% IACS for HE). However, this alloy also exhibited the highest hardness (77 HRB vs. 69 HRB for HP and 70 HRB for HE), the highest compressive strength (443 MPa vs. 386 MPa for HP and 378 MPa for HE), and the best hardness retention among the investigated alloys. The results illustrate that the alloy prepared by the HVC method exhibits high softening temperature and good mechanical properties at high temperatures, which imply long service life when used as spot-welding electrodes.

Keywords

dispersion-strengthened alloys / copper alloys / alumina / preparation methods / microstructure / properties

References

[1] Need R.F., Alexander D.J., Field R.D., Livescu V., Papin P., Swenson C.A., Mutnick D.B. The effects of equal channel angular extrusion on the mechanical and electrical properties of alumina dispersion-strengthened copper alloys. Mater. Sci. Eng. A, 2013, 565, 450.

[2] Rajkovic V., Bozic D., Devecerski A., Jovanovic M.T. Characteristic of copper matrix simultaneously reinforced with nano- and micro-sized Al₂O₃ particles. Mater. Charact., 2012, 67, 129.

[3] Besterci M., Kohútek I., Velgosová O. Microstructural parameters of dispersion strengthened Cu-Al₂O₃ materials. J. Mater. Sci., 2008, 43(3): 900.

[4] Li G.B., Sun J.B., Guo Q.M., Wang R. Fabrication of the nanometer Al₂O₃/Cu composite by internal oxidation. J. Mater. Process. Technol., 2005, 170(1-2): 336.

[5] Hussain Z., Kit L.C. Properties and spot welding behaviour of copper-alumina composites through ball milling and mechanical alloying. Mater. Des., 2008, 29(7): 1311.

[6] Lee D.W., Kim B.K. Nanostructured Cu-Al₂O₃ composite produced by thermochemical process for electrode application. Mater. Lett., 2004, 58(3-4): 378.

[7] Hwang S.J., Lee J. Mechanochemical synthesis of Cu-Al₂O₃ nanocomposites. Mater. Sci. Eng. A, 2005, 405(1-2): 140.

[8] Lee J., Kim Y.C., Lee S., Kim N.J., Ahn S. Correlation of the microstructure and mechanical properties of oxide- dispersion-strengthened coppers fabricated by internal oxidation. Metall. Mater. Trans. A, 2004, 35(2): 493.

[9] Dash K., Ray B.C., Chaira D. Synthesis and characterization of copper-alumina metal matrix composite by conventional and spark plasma sintering. J. Alloys Compd., 2012, 516, 78.

[10] Yan Z.Q., Chen F., Cai Y.X. High-velocity compaction of titanium powder and process characterization. Powder Technol., 2011, 208(3): 596.

[11] Skoglund P. High density PM parts by high velocity compaction. Powder Metall., 2001, 44(3): 199.

[12] Khan D.F., Yin H.Q., Li H., Abideen Z., Asadullah Qu X.H., Ellahi M. Effect of impact force on Ti-10Mo alloy powder compaction by high velocity compaction technique. Mater. Des., 2014, 54, 149.

[13] Yan Z.Q., Chen F., Cai Y.X., Zheng Y.K. Microstructure and mechanical properties of in-situ synthesized TiB whiskers reinforced titanium matrix composites by high-velocity compaction. Powder Technol., 2014, 267, 309.

[14] Ying D.Y., Zhang D.L. Processing of Cu-Al₂O₃ metal matrix nanocomposite materials by using high energy ball milling. Mater. Sci. Eng. A, 2000, 286(1): 152.

[15] Sethi G., Myers N.S., German R.M. An overview of dynamic compaction in powder metallurgy. Int. Mater. Rev., 2008, 53(4): 219.

[16] Chen F., Yan Z.Q., Cai Y.X., Zheng Y.K. Effect of high-velocity compaction methods on characteristics of electrolytic copper powder. Mater. Sci. Eng. Powder Metall., 2014, 19(1): 116.

[17] Ashby M.F., Bahk S., Bevk J., Turnbull D. The influence of a dispersion of particles on the sintering of metal powders and wires. Prog. Mater. Sci., 1980, 25(1): 1.

[18] Hussain Z., Keong K.H. Studies on alumina dispersionstrengthened copper composites through ball milling and mechanical alloying method. J. Teknol. A, 2005, 43, 1.

[19] Li M.X., Luo J., Guo Z.M. Study on nanometer Al₂O₃ dispersion-strengthened copper composites fabricated by internal oxidation method. Powder Metall. Technol., 2011, 29(3): 214.