Al-15%Mg_2Si复合材料中二元相的研究  

Study on Binary Phase of Al-15%Mg_2Si Composite

作　　者：刘桐宇[1] 李英民[1] 任玉艳[1] 

机构地区：[1]沈阳工业大学,辽宁沈阳110870

出　　处：《稀有金属材料与工程》2017年第10期2870-2876,共7页Rare Metal Materials and Engineering

基　　金：沈阳市科学技术项目(F15-199-1-11);辽宁省自然科学基金(20102167)

摘　　要：用原位内生法制备了Al-15%Mg_2Si(质量分数,下同)复合材料,通过XRD测试,定性和定量地分析材料中的相成分和相含量。利用Reflex模拟Al-Mg-Si系合金的XRD图谱,并与XRD测试结果对比。利用CASTEP中基于密度泛函理论的第一性原理方法,对Al-Mg_2Si复合材料中的Mg_2Si相和Mg_(17)Al_(12)相的平衡晶格常数,热力学参数和弹性性质做了系统的研究,分析两相的稳定性和力学性能。XRD分析结果显示,Al-15%Mg_2Si复合材料中仅含有α-Al相和Mg_2Si相,且Mg_2Si相的质量分数为14.9%。模拟与实验中,相同晶面指数的XRD标定值相差很小,实验值验证了模拟值的可靠性。模拟值证实Al-Mg_2Si复合材料中,理论上只形成α-Al相和Mg_2Si相。CASTEP计算结果表明,Al-Mg_2Si复合材料中的Mg_2Si相较Mg_(17)Al_(12)相易于形成,且稳定性较好。Mg_2Si相的弹性模量E,剪切模量G,体模量B均大于Mg_(17)Al_(12)相,Mg_2Si相的力学性能较好,但脆性较大,且塑性较差。Al-15 wt%Mg_2Si composite was prepared by an in-situ method. The phase components and content were analyzed qualitatively and quantitatively by XRD. The XRD pattern of Al-Mg-Si alloy was simulated by Reflex and the simulated result was compared with the XRD result. Lattice constants, thermodynamic parameter and elastic constant of Mg_2Si phase and Mg_（17）Al_（12） phase in Al-Mg_2Si composite were investigated by first-principle calculations from CASTEP program based on density functional theory to compare the stability and mechanical properties. There are only α-Al phase and Mg_2Si phase in Al-15 wt%Mg_2Si composite as shown in XRD result; and the mass fraction of Mg_2Si phase is 14.9%. The differences of XRD indices with the same crystal plane（h k l） between simulation and test are fractional. Therefore, the simulated result by Reflex is reliable. Only α-Al phase and Mg_2Si phase are formed in theory shown by simulation. The calculated heats of formation and cohesive energies show that Mg_2Si phase is easy to form and the alloying ability is stronger. Mg_2Si phase is more stable than Mg_（17）Al_（12） phase. Elastic modulus（E）, shear modulus（G）, and bulk modulus（B） of Mg_2Si phase is higher than that of Mg_（17）Al_（12） phase. However, the friability of Mg_2Si phase is higher and the plasticity is lower.

关 键 词：Al-15%Mg2Si复合材料 CASTEP 第一性原理 REFLEX XRD定量分析 

分 类 号：TB333[一般工业技术—材料科学与工程]