Ca,Sr加入对Mg-Al基合金显微组织和蠕变性能的影响  

Effect of Ca and Sr on microstructure and creep property of Mg-Al based alloy

作　　者：白晶[1] 孙扬善[1] 薛烽[1] 强婧[1] 陶卫建 

机构地区：[1]东南大学材料科学与工程学院,南京211189 [2]南京云海特种金属有限公司,南京211221

出　　处：《东南大学学报（自然科学版）》2007年第4期639-644,共6页Journal of Southeast University：Natural Science Edition

基　　金：国家高技术研究发展计划(863计划)资助项目(2001AA331030-01);江苏省自然科学基金预研资助项目(BK2004208);东南大学优秀博士学位论文基金资助项目

摘　　要：系统研究了Ca,Sr加入对Mg-4Al基合金(AM40)显微组织和蠕变性能的影响.铸态AM40显微组织中除了α-Mg基体外,只有少量的短棒状β-Mg17Al12颗粒.Ca加入AM40合金后能观察到沿枝晶间分布的层片状Mg2Ca相和细小的盘状Al2Ca颗粒.当Ca与Sr同时加入AM40时,显微组织中的晶界相除了Mg2Ca外,出现了另一种块状的三元Mg-Al-Sr相.由于Ca和Sr的加入,合金显微组织中形成了热稳定性很高的中间相Mg2Ca,Al2Ca和Mg-Al-Sr相,并抑制了β相的形成,因而大幅度提高了合金的抗蠕变性能.随着Ca和Sr加入量的增加,合金的抗蠕变性能得到进一步提高.在块状Mg-Al-Sr三元相和层片Mg2Ca相的共同作用下,Ca和Sr的复合合金化比单一Ca合金化对改善合金抗蠕变性能更有效.The microstructures and creep resistance of Mg-4Al （AM40） based alloys with Ca and Sr additions have been investigated. The as-cast microstructure of Mg-4Al alloy consists of α-Mg matrix and a small amount of rod-shaped β-Mg17 Al12 particles. After adding Ca into AM40 lamellar Mg2Ca at grain boundary and tiny disc-shaped Al2Ca particles in the matrix grains can be observed. A bulky Mg-Al-Sr ternary phase appears at grain boundaries besides Mg2Ca after Ca and Sr additions. The creep resistance of the alloys increase significantly with Ca and Sr additions due to the elimination of β-Mg17Al12 phase and the formation of high thermostable Mg2Ca, Al2Ca and Mg-Al- Sr interphases. The creep properties of the alloys can be further improved when the contents of Ca and Sr increase. The alloys with combined additions of Ca and Sr show higher creep properties than that with simple additions of Ca due to the formation of two interphases Mg2Ca and Mg-Al-Sr at grain boundaries.

关 键 词：耐热镁合金 锶 钙 显微组织 抗蠕变性能 

分 类 号：TG146.22[一般工业技术—材料科学与工程]