Microstructure characteristics of Cu-31.4%Mn alloy under laser rapid solidification condition

Laser rapid solidification experiments have been performed on Cu-31.4% Mn alloy to investigate the response of microstructure pattern and cellular spacing selection to the variation of growth rate. With increasing growth rate, microstructures go from light band to elongated cell, regular cell, then elongated cell and planar-like structure, and finally to absolute stability planar in turn. Experimental results show that there is a distribution range in cellular spacing under the laser rapid solidification condition, the distribution range and the average spacing decrease with the increase of the growth rate. The maximum, lambda(max), minimum, lambda(min), and average primary spacing, lambda, as functions of growth rate v(s), can be given by lambda(max)=6. 82 v(s)(-0.33), lambda(min)=2.89v(s)(-0.28) and lambda=4.35v(s)(-0.31), respectively. The experimental results are compared with the Hunt-Lu numerical model for rapid cellular/dendritic growth,and a reasonable agreement is found.