Synthesis of CuCr and CuCrAg alloy with nano-ceramic dispersion by mechanical alloying and consolidation by laser assisted sintering

摘要

Cu-4.5Cr and Cu-4.5Cr-3Ag (in wt%) alloys without or with 10 wt% nanocrystalline Al_2O_3 and ZrO_2 dispersion have been synthesized by mechanical alloying or milling and consolidated by laser assisted sintering in Ar atmosphere. Microstructural characterization by scanning and transmission electron microscopy and phase analysis by X-ray diffraction suggest that the alloyed matrix undergoes significant grain growth after sintering while the dispersoids retain their ultrafine size and uniform distribution in the matrix. The dispersion of nano-Al_2O_3 is more effective than that of nano-ZrO_2 in enhancing the mechanical properties due to the smaller initial particle size of Al_2O_3 than that of ZrO_2. In general, laser sintering of mechanically alloyed Cu-4.5Cr and Cu-4.5Cr-3Ag alloys with 10 wt% nanocrystalline Al_2O_3 at 100 W laser power and 1-2 mm s~(-1) scan speed yields the optimum combination of high density (7.1-7.5 mg m~(-3)), hardness (165-225 VHN), wear resistance and electrical conductivity (13-20% IACS).