(1. 河南理工大学 材料科学与工程学院，焦作 454000；
2. 西安理工大学 材料科学与工程学院，西安 710048)
摘 要: 利用往复挤压制备细晶Mg-4Al-2Si合金，采用OM、XRD和SEM分析合金组织，在150 ℃和1.33×10−3 s−1初始应变速率下测试合金的拉伸性能。结果表明：铸态组织由α-Mg、β-Mg17Al12、共晶型汉字状Mg2Si和少量初生块状Mg2Si组成。经过8道次往复挤压后，α-Mg和Mg2Si颗粒的尺寸分别为2.1和1.3 μm，高温抗拉强度、屈服强度、伸长率和拉伸强度保持率分别为250 MPa、197 MPa、62%和88%。优良的高温性能归因于细小的基体组织和稳定的Mg2Si颗粒对晶界的有效钉扎作用。
关键字: 镁合金；Mg-4Al-2Si合金；Mg2Si；往复挤压；高温拉伸性能
prepared by reciprocating extrusion
（1. School of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo 454000, China;
2. School of Materials Science and Engineering, Xi’an University of Technology, Xi’an 710048, China）
Abstract:The fine grained Mg-4Al-2Si alloy was prepared by reciprocating extrusion (RE). The microstructures were analyzed by X-ray diffractometry (XRD), optical microscopy (OM) and scanning electron microscopy (SEM). The elevated temperature tensile properties were measured at 150 ℃ with an initial strain rate of 1.33×10−3 s−1. The results show that the as-cast alloy consists of α-Mg, β-Mg17Al12 and Chinese script Mg2Si formed during the eutectic reaction and some primary block Mg2Si. After 8 passes reciprocating extrusion (RE), the average sizes of α-Mg grain and Mg2Si particle are 2.1 and 1.3 mm, respectively. The elevated temperature ultimate tensile strength, yield strength, elongation and retaining rate of ultimate tensile strength are 250 MPa, 197 MPa, 62% and 88%, respectively. The excellent elevated temperature properties are ascribed to the fine matrix and thermally stable Mg2Si particles, which can firmly pin the grain boundaries.
Key words: Mg alloy; Mg-4Al-2Si alloy; Mg2Si; reciprocating extrusion; elevated temperature tensile properties
