La_(2)O_(3)对AZ31镁合金表层扩渗Zn的影响  

Effect of La_(2)O_(3)on the Zn Diffusion in AZ31 Magnesium Alloy Surface

作　　者：钟强 李秀兰 罗宏 ZHONG Qiang;LI Xiu-lan;LUO Hong(School of Materials Science and Engineering,Sichuan University of Science and Engineering,Zigong 643000,China;School of Mechanical Engineering,Sichuan University of Science and Engineering,Yibin 644000,China)

机构地区：[1]四川轻化工大学材料科学与工程学院,四川自贡643000 [2]四川轻化工大学机械工程学院,四川宜宾644000

出　　处：《材料保护》2021年第11期31-34,47,共5页Materials Protection

基　　金：四川轻化工大学研究生创新基金项目(y2020041)资助。

摘　　要：通过在AZ31镁合金表面固态扩渗Zn,研究La_(2)O_(3)稀土元素对AZ31表面固态扩渗Zn层形成机理的影响。在390℃下,选用La_(2)O_(3)+Zn粉为渗剂,分别在2,4,6 h的条件下对AZ31进行固态扩渗,然后借助金相显微镜和X射线衍射仪(XRD)对扩渗层的物相组成和显微结构进行研究,探索和建立La_(2)O_(3)稀土对AZ31扩渗Zn机理影响的模型。结果表明:在扩渗2 h时,跃迁能量不足,没有渗层产生;在4 h时,发生合金转变Mg_(0.97)Zn_(0.03)+Zn→MgZn+MgZn_(2);6 h时发生包晶反应L+MgZn_(2)→Mg_(2)Zn_(3);在390℃下对AZ31镁合金进行Zn+La_(2)O_(3)粉的固态扩渗,La_(2)O_(3)由于活泼的化学性,破坏了AZ31基体表层结构,加快了渗剂Zn的扩渗速度,前期主要为原子扩散,中期为液态扩散+合金转变Mg_(0.97)Zn_(0.03)+Zn→MgZn+MgZn_(2),后期为液态扩散+反应扩散(包晶)L+MgZn_(2)→Mg_(2)Zn_(3)。The effect of La_(2)O_(3)rare earth elements on the formation mechanism of AZ31 surface solid diffused Zn layer was studied by solid diffused Zn on the surface of AZ31 magnesium alloy.Under the conditions of 390℃and selecting La_(2)O_(3)+Zn powders as infiltrate,the AZ31 magnesium alloy surface was carried out by solid diffusion treatment for 2 h,4 h and 6 h,respectively.Subsequently,the phase constituents and micro structure of the diffusion alloyed coating were analyzed by metallurgical microscope and X-ray diffraction(XRD),and a model of the influence of La_(2)O_(3)rare earth on the mechanism of AZ31 diffusion of Zn was further explored and established.Results showed that when the diffusion time was 2 h,the transition energy was not enough to generate the infiltrating layer.At 4 h of diffusion,the alloy changed from Mg_(0.97)Zn_(0.03)+Zn→MgZn+MgZn_(2).At 6h of diffusion,the peritectic reaction occurred from L+MgZn_(2)→Mg_(2)Zn_(3).Under the temperature of 390℃,the solid diffusion of Zn+La_(2)O_(3)powder was carried out for AZ31 magnesium alloy.Because of active chemistry of La_(2)O_(3),La_(2)O_(3)destroyed the surface structure of AZ31 matrix and speeded up the diffusion speed of infiltrate Zn.In the early stage,the main diffusion was atomic difusion;in the middle stage,the main diffusion was liquid diffusion+alloy transformation Mg_(0.97)Zn_(0.03)+Zn→MgZn+MgZn_(2);in the later stage,the main diffusion was liquid diffusion+reaction diffusion(peritectic)L+MgZn_(2)→Mg_(2)Zn_(3).

关 键 词：AZ31 热扩渗 ZN La_(2)O_(3) 

分 类 号：TG156.8[金属学及工艺—热处理]