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Ca对Mg-5Al-8Zn-xCa镁合金显微组织与力学性能的影响
宋佩维
陕西理工大学材料科学与工程学院, 矿渣综合利用环保技术国家地方联合工程实验室, 陕西省冶金渣资源化利用工程技术研究中心, 汉中 723001
摘要:
文 摘 采用重力铸造法制备了Mg-5Al-8Zn-xCa(x= 0, 1.75, 2.0, 2.25, 2.5, 2.75, 3.0, 质量分数, %)合金。使用X射线衍射仪(XRD)、光学显微镜(OM)和扫描电镜(SEM)等研究了Ca含量对合金组织与力学性能的影响。结果表明:铸态Mg-5Al-8Zn-xCa合金主要由a-Mg基体、b-Mg17Al12相、Mg32(Al, Zn)49相及MgZn2相和Al2Ca相组成。当Ca含量从1.75%增加到2.75%时,基体晶粒显著细化,b-Mg17Al12相由粗大的连续网状转变为细小的断续网状分布于晶界上,层片状Al2Ca相也显著细化,此时合金的拉伸强度达到最大值138 MPa,较未加Ca时提高了27.8%;Ca含量继续增加至3.0%,晶粒又发生粗化,合金拉伸强度发生下降;拉伸断裂形式均为准解理脆性断裂。
关键词:  Ca  镁合金  显微组织  力学性能
DOI:10.12044/j.issn.1007-2330.XXXX.XX.001
分类号:TG146.22
基金项目:陕西省自然科学基金资助项目 (2010JM6009);陕西省教育厅科研计划资助项目(2010JK470)
Effects of Ca content on microstructures and mechanical properties of Mg-5Al-8Zn-xCa magnesium alloys
SONG Peiwei
School of Materials Science and Engineering, Shaanxi University of Technology, National and Local Join Engineering Laboratory for Slag Comprehensive Utilization and Environmental Technology, Shaanxi Provence Engineering & Technology Research Center of Resource Utilization of Metallurgical Slag, Hanzhong 723001
Abstract:
Mg-5Al-8Zn-xCa( x= 0, 1.75, 2.0, 2.25, 2.5, 2.75 and 3.0 wt%) Mg alloys were prepared by gravity casting. The effects of Ca content on microstructures and mechanical properties of the alloys were investigated by XRD, OM and SEM. The results show that the as-cast Mg-5Al-8Zn-xCa alloy is composed mainly of a-Mg matrix, b-Mg17Al12, Mg32(Al, Zn)49, MgZn2 and Al2Ca phases. With the increase of Ca content from 1.75% to 2.75%, the matrix grain is obvious refinement, the morphological change in b-Mg17Al12 phase occurs from coarse continuous network to fine intermittent network and distributed on the grain boundaries, the lamella-type phase Al2Ca is obvious refinement too, meanwhile the tensile strength of the alloy at room temperature reaches maximum, it is 138 MPa, increased by 27.8%, compared with the alloy with absence of Ca addition. When the Ca content reaches 3.0%, the grain is coarsened once more, meanwhile the tensile strength of the alloy decreased. The tensile fractures of the alloys are characterized by quasi-cleavage at room temperature.
Key words:  Ca  Mg alloy  microstructure  mechanical property