激光熔覆Ni-Sn共晶合金的组织演变  

Microstructure Evolution of Ni-Sn Eutectic AUoy in Laser Cladding

作　　者：徐嘉隆[1] 林鑫[1] 汪志太[1] 曹永青[1] 黄卫东[1] 

机构地区：[1]西北工业大学凝固技术国家重点实验室,陕西西安710072

出　　处：《应用激光》2012年第1期1-7,共7页Applied Laser

基　　金：国家自然科学基金资助项目(项目编号:50971102);国家重点基础研究发展计划资助项目(项目编号:2011CB610402);高等学校学科创新引智计划资助项目(项目编号:08040);凝固技术国家重点实验室(西北工业大学)自主研究课题资助项目(项目编号:16-TZ-2007;和39-QZ-2009)

摘　　要：采用激光熔覆方法制备了Ni-Sn共晶合金熔覆层,通过对不同扫描速度下熔覆层的组织特征进行分析,发现熔覆层组织主要由α-Ni+Ni-Sn层片共晶组成,层片间距相比基材明显细化,并且在熔覆层与基材界面处,共晶层片基本沿熔覆层沉积方向外延生长,随着远离基材,层片共晶生长方向逐渐向激光扫描方向偏转,在垂直激光扫描方向的熔覆层横截面呈现出类等轴的共晶团组织。随着扫描速度的增加,熔覆层中的带状组织和顶部的少量非规则共晶团逐渐消失,共晶层片间距减小。用描述快速共晶生长的TMK模型对熔覆层底部的共晶层片间距随激光扫描速度的变化规律进行了分析,实验结果与理论模型基本吻合。Ni-Sn eutectic deposits were prepared by laser cladding with different scanning velocity,and the microstructure of deposits were examined.It is found that,the as-deposited microstructure consists mainly ofα-Ni＋ Ni_3Sn lamellar eutectic,and the eutectic lamellar spacing is refined significantly compared with that of substrate.At the interface between deposits and the substrate, lamellar eutectic grows epitaxially along the deposition direction.With the increase of the distance from the substrate,lamellar eutectic tends to grow along the laser scanning direction gradually,which leads to the formation of equiaxed-like eutectic clusters in the cross section of deposits.As the laser scanning velocity increases,the eutectic lamellar spacing decreases,meanwhile,the anomalous eutectic at the top of deposits and banded structure in the deposits disappear gradually.The relationship between eutectic lamella spacing and laser scanning velocity at the bottom of deposits was further analyzed using TMK models,and the experiment results shows a reasonable agreement with the models＇ prediction.

关 键 词：激光熔覆 Ni-Si合金 共晶 组织演变 

分 类 号：TG111.4[金属学及工艺—物理冶金]