IMPROVING THE SURFACE PROPERTY OF TC4 ALLOY BY LASER NITRIDING AND ITS MECHANISM

作     者：Y.L. Yang G.J. Zhao D. Zhang C.S. Liu 

作者机构：Gollege of Sdence Northeastern University Shenyang 110004 Ghina College of Material and Metallurgy Northeastern University Shenya g 110004 China 

出 版 物：《Acta Metallurgica Sinica(English Letters)》 (金属学报（英文版）)

年 卷 期：2006年第19卷第2期

页      面：151-156页

核心收录：

学科分类：080503[工学-材料加工工程] 08[工学] 0805[工学-材料科学与工程（可授工学、理学学位）] 0802[工学-机械工程] 080201[工学-机械制造及其自动化] 

基　　金：the Liaoning Provincial Doctor Startup Foundation Committee of China(20051012) 

主　　题：laser nitridation surface property Ti alloy 

摘      要：The mixing technology of laser and heated nitrogen was applied to improve the surface hardness of titanium alloy （ TC4 ）. The samples were nitrided with laser power density of 6.S × 10^6SW. cm^-2, the scanning speed varioas from 100 to 500mm ·min^-1. The nitrogen gas was pre-heated to 300℃ to accelerate the nitriding process. Some interested samples were tested with XRD method （X-ray diffraction） to analyze the composition of nitrides, and the surface hardness of HV was measured. The results show that TiN and Ti2N were formed on the surface of Ti alloy with proper nitriding parameters, but TiN is the main composition. The surface hardness increased by three times, which is from the original value of 269to 794kg·mm^-2. The mechanism of the mixing technology is considered mainly of the activation of nitrogen by laser power and the pre-heated process which accelerated the nitriding process. The nitridation process can be considered as six steps given in detail. The result by analyzing the mechanism of improving the surface property of TiAl alloy shows the improvement of surface property due to two factors： the first reason is the result of laser annealing, and the second one is the formation of TiN.