Effects of TiB2 on microstructure of nano-grained Cu–Cr–TiB2 composite powders prepared by mechanical alloying

Nano-grained CuCr25 and CuCr25–(2 wt%–10 wt%)TiB2 composite powders were prepared by mechanical alloying method. The milled powders were characterized by SEM, FSEM, EDS, XRD, TEM and HTEM. The results indicate that average grain size of Cu, Cr and TiB2 are less than 50 nm and each component disperses uniformly. The grain size of Cu and Cr decreased and the lattice distortion increased gradually as the TiB2 content increased from 2 wt% to 10 wt%. The ultrafine TiB2 particles play the role of “micro-milling balls” to compact, micro-etch, micro-frict and micro-cut with Cu and Cr so that the grain refinement and lattice strain are promoted.