激光快速凝固条件下Cu-27.3%Mn合金的微观组织特征

MICROSTRUCTURE FEATURES OF Cu-27.3%Mn ALLOY UNDER LASER RAPID REMELTING AND SOLIDIFICATION CONDITION

利用 ＣＷ ＣＯ_２激光器对 Ｃｕ—２７．３％Ｍｎ进行了系列表面熔凝实验，对该合金的组织形态和胞晶间距选择规律进行了研 究结果表明：随着生长速度的提高，组织形态由低速平界面向细胞晶和高速绝对稳定平界面转变在快速凝固条件下．Ｃｕ—Ｍｎ合＆ 的胞晶间距存在一个较大的选择范围，最大、最小和平均胞晶间距与生长速度的关系分别为 λｍａｘ＝４．８８ｖｓ~０．２６， λｍｉｎ=２．３５ｖｓ~０．２２和 λ＝ ３．６６ｖｓ~０．２５实验结果与

Laser rapid solidification experiments have been performed on Cu- 27.3%Mn alloy to investigate the response of microstructure pattern and cellular spacing selection to the variation of growth rate. As growth rate increases, microstructure goes from light band to fine cell and absolute stability planar. Experimental results show that there exists a wide distribution range in cellular spacing under laser rapid solidification condition, the distribution range and the average spacing decrease w ith increase of the growth rate. The maximum, λ=Max, minimum, λ=min, and average primary spacing, λ, as functions of growth rate vs, can be given by λmax= 4.88vs^0.26, λmin = 2.35vs0.22 and λ= 3.66vs0.25, respectively. The experimental results are compared with the current KGT model for rapid cellular/dendritic growth, and a reasonable agreement is found.