合金元素Al对定向凝固镁合金组织、晶粒取向和力学性能的影响

Effect of Alloying Element Al on the Microstructure, Grain Orientations and Mechanical Properties of Magnesium Alloys

使用自行设计的定向凝固炉,制备了纯Mg、Mg-0.5Al和Mg-1Al的定向凝固铸件,采用金相分析、XRD分析和力学性能测试的方法,对其组织、晶粒取向和在298 K、423 K时的力学性能进行了研究和分析。结果表明:使用该种定向凝固技术和方法,随着合金元素Al的增加,晶粒得到了细化。定向凝固纯Mg、Mg-0.5Al、Mg-1Al晶粒生长的主要方向分别是[1012]和[1013]、[1120]和[1012]、[1120]。298 K时,定向凝固纯Mg、Mg-0.5Al、Mg-1Al的抗拉强度和伸长率分别为56 MPa和18%、127MPa和3%、153 MPa和9.5%;423 K时,定向凝固纯镁、Mg-0.5Al、Mg-1Al的抗拉强度和伸长率为57 MPa和38%、120 MPa和14%、134 MPa和19.5%,使定向凝固镁合金有较优良的高温力学性能。

The self-designed directional solidification equipment was used in this paper to manufacture the casting directionally solidified pure Mg, Mg-0.5Al and Mg-1Al castings. The investigations have been carried out by means of metallurgical analysis, X-ray diffraction analysis and mechanical properties testing, and the microstructure, grain orientations and mechanical properties in 298 K and 423 K were studied. The results show that by using this directional solidification method, grain refinement was obtained with the increased alloying element Al. The main directions of the grain growth of pure Mg, Mg-0.5Al, Mg-1Al were [10-12] and [10-13],[11-20 ]and [10-12], [11-20] respectively. The tensile strength and the elongation of directionally solidified pure Mg, Mg-0.5Al and Mg-1Al in 298 K were 56 MPa and 18%, 127 MPa and 3%, 153 MPa and 9.5%. At 423 K, the tensile strength and the elongation of directionally solidified pure Mg, Mg-0.5Al and Mg-1Al were 57 MPa and 38%, 120 MPa and 14%, 134 MPa and 19.5% respectively. Thus, the directionally solidified Mg alloys represented excellent high temperature mechanical properties.