摘要
以AZ91-1.5Si-0.4Ca为对象(以AZ91为参照),通过设计并压铸成型4种厚度的板状试样获得了4个凝固速率。首先对各壁厚试样的凝固速率进行了数值模拟,并对2种合金试样的显微组织、室温和180℃拉伸性能、拉伸断口形貌进行了对比研究。结果表明:AZ91-1.5Si-0.4Ca中的Si与Mg生成Mg_2Si,Ca主要以固溶的形式存在;Si和Ca有一定的晶粒细化效用。随着凝固速率增加,AZ91-1.5Si-0.4Ca中的Mg_2Si相由粗大的多边形及汉字状向细小的多边形颗粒及短棒转变。随着凝固速率增加,2种合金试样的室温和180℃力学性能提高,AZ91-1.5Si-0.4Ca室温和180℃强度受凝固速率影响大于AZ91,伸长率受凝固速率影响则小于AZ91。当壁厚小于2.5 mm时,AZ91-1.5Si-0.4Ca的180℃强度高于AZ91;当壁厚小于3 mm时,AZ91-1.5Si-0.4Ca的室温强度高于AZ91。
Specimens of AZ91-1.5Si-0.4Ca and AZ91 with different section thickness were prepared by HPDC （high pressure die-casting）. The solidification rate of the HPDC specimens was numerically simulated. The microstructure, tensile properties and fracture morphology at the ambient temperature and 180℃ of the specimens were investigated. The results show that Si and Mg form Mg2Si phase and Ca mainly dissolves in the matrix. Besides, Si and Ca have some effect on grain refinement of the Mg matrix. With the increase in solidification rate, the Mg2Si phase in AZ91-1.5Si-0.4Ca turns from bulky polygons and Chinese script type to fine polygons and short rod. The mechanical properties of AZ91-1.5Si-0.4Ca and AZ91 at ambient temperature and 180℃ increase with the increase of solidification rate. The influence of section thickness on tensile strength of AZ91-1.5Si-0.4Ca is greater than that of AZ91, but the influence on elongation is less than that of AZ91. Furthermore, the tensile strength of AZ91-1.5Si-0.4Ca at 180℃ is higher than that of AZ91 when the section thickness is less than 2.5 mm, and the tensile strength of AZ91-1.5Si-0.4Ca at ambient temperature is higher than that of AZ91 when the section thickness is less than 3 mm.
作者
游国强
明玥
闫鹏
马小黎
童帮华
You Guoqiang;Ming Yue;Yan Peng;Ma Xiaoli;Tong Banghua(Chongqing University,Chongqing 400044,China;National Engineering Research Center for Magnesium Alloy Materials,Chongqing 400030,China;Nanchong Zhaoqing Machinery Manufacturing Co.Ltd,Nanchong 637800,China)
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2018年第8期2392-2403,共12页
Rare Metal Materials and Engineering
基金
重庆大学大型仪器设备开放基金(201512150010)
