Surface nanocrystallization of Cu-Cr alloy by a high power density continuous laser beam

A nanostructured surface layer of similar to 300 mu m thickness was fabricated on Cu-30Cr (wt%) hypereutectic alloy by a continuous laser beam with high power density (1.08 x 10(7) W/cm(2)). The average grain size of Cr-rich particles was refined to similar to 40 nm, and the solid solubility limit of Cr in Cu was extended to 1.96 at. %. Experimental results show that the dispersion of nano-sized Cr-rich spheroids in Cu-rich matrix was attributed to the Brownian motion of Cr-rich spheroids, and the high cooling rate (5.75 x 10(6) K/s) during liquid phase separation which inhibits the collisions between Cr-rich spheroids. (C) 2018 Published by Elsevier B.V.