等温处理对Mg-3Y-4Nd-1Ni-0.5Zr合金半固态坯料件显微组织的影响  

Influence of isothermal treatment on microstructure of Mg-3Y-4Nd-1Ni-0.5Zr alloy semi-solid billet

作　　者：张虹桃 邓涛 鲁天慧 林芯仪 苏红亮 权高峰[2] 曹万平 Zhang Hongtao;Deng Tao;Lu Tianhui;Lin Xinyi;Su Hongliang;Quan Gaofeng;Cao Wanping(AVIC Chengdu Aircraft Industry(Group)Co.,Ltd.,Chengdu 610092,China;School of Materials Science and Engineering,Southwest Jiaotong University,Chengdu 610031,China)

机构地区：[1]航空工业成都飞机工业(集团)有限责任公司,四川成都610092 [2]西南交通大学材料科学与工程学院,四川成都610031

出　　处：《锻压技术》2023年第5期51-60,共10页Forging & Stamping Technology

基　　金：四川省科技厅重点研发计划项目(2017GZ0399)。

摘　　要：采用半固态等温加热法,观察Mg-3Y-4Nd-1Ni-0.5Zr合金在不同半固态温度(580、595、610和625℃)和保温时间(5、15、30和60 min)下的微观组织形貌,研究工艺参数对显微组织演变的影响,得到晶粒粗化机制和最佳半固态触变成形工艺参数。结果表明:经过等温加热处理后,Mg-3Y-4Nd-1Ni-0.5Zr合金组织由细小的α-Mg晶粒转变为球形颗粒;随着半固态温度和保温时间的增加,Mg-3Y-4Nd-1Ni-0.5Zr合金的平均晶粒尺寸、液相率和形状系数逐渐增加。当半固态温度低于595℃或保温时间少于30 min时,半固态显微组织演变主要以晶粒长大为主,粗化合并机制起主导作用;当半固态温度高于610℃或保温时间超过30 min时,半固态显微组织液相增加和固相颗粒球状化,Ostwald熟化机制起主导作用。最佳工艺参数为:半固态温度为625℃、保温时间为15 min,此工艺参数下的Mg-3Y-4Nd-1Ni-0.5Zr合金的平均晶粒尺寸、液相率和形状系数分别为(60.9±3.1)μm,(31.2±1.4)%和(64.1±0.4)%。The microstructure of Mg-3Y-4Nd-1Ni-0.5Zr alloy was observed by semi-solid isothermal heating method under different semi-solid temperatures(580,595,610 and 625℃)and holding times(5,15,30 and 60 min),and the influences of process parameters on microstructure evolution were investigated to obtain the grain coarsening mechanism and optimum semi-solid thixoforming process parameters.The results show that Mg-3Y-4Nd-1Ni-0.5Zr alloy structure changes from fineα-Mg grains to spherical particles after isothermal heating treatment,and the average grain size,liquid fraction and shape coefficient of Mg-3Y-4Nd-1Ni-0.5Zr alloy increase with the increasing of semi-solid temperature and holding time.When the semi-solid temperature is lower than 595℃or the holding time is less than 30 min,the microstructure evolution of semi-solid microstructure is mainly dominated by grain growth,and coarsening merge mechanism plays a leading role.When the semi-solid temperature is higher than 610℃or the holding time is more than 30 min,the liquid phase of the semi-solid microstructure increases,the solid particles become spheroidal,and the Ostwald ripening mechanism plays a dominant role.The optimal process parameters are the semi-solid temperature of 625℃and the holding time of 15 min.Under the optimal process parameters,the average grain size,liquid fraction and shape coefficient of Mg-3Y-4Nd-1Ni-0.5Zr alloy are(60.9±3.1)μm,(31.2±1.4)%and(64.1±0.4)%,respectively.

关 键 词：等温加热法 稀土镁合金 半固态温度 保温时间 粗化合并机制 Ostwald熟化机制 

分 类 号：TG146.22[一般工业技术—材料科学与工程]