论文部分内容阅读
采用合金平衡组织结构分析法,利用扫描电镜组织观察、电子探针定量成分分析以及X射线衍射和透射电子衍射结构分析,对Mg-Zn-Ca系富Mg区域300°C的相平衡关系及平衡相成分进行研究。结果表明:300°C时,2个三元化合物T1和T2都可与Mg基固溶体相平衡。T1相是一个线性化合物相,成分为15%Ca(摩尔分数),20.5%～48.9%Zn,余量为Mg。T1相为六方晶体结构,晶格常数为:a=0.992～0.945nm,c=1.034～1.003nm,随T1相中Zn含量的增加而减少。化合物T2相也是六方结构,成分为26.4%～28.4%Mg,63.2%～65.5%Zn以及7.1%～8.4%Ca。300°C时,Zn在Mg基固溶体中的溶解度随Ca的加入而增大,最大溶解度达到3.7%。在Mg-Zn-Ca系中300°C等温截面相图的富Mg区域存在着三相区α-Mg+Mg2Ca+T1,α-Mg+T1+T2,α-Mg+T2+MgZn和MgZn+T2+Mg2Zn3。
The equilibrium structure and equilibrium of Mg-Zn-Ca-rich Mg-Zn-Mg region at 300 ° C were investigated by means of alloy equilibrium microstructure analysis, scanning electron microscopy, electron probe quantitative composition analysis and X-ray diffraction and transmission electron diffraction analysis. Phase components were studied. The results show that both ternary compounds T1 and T2 can be balanced with the Mg-based solid solution at 300 ° C. The T1 phase is a linear compound phase with 15% Ca (mole fraction), 20.5% -48.9% Zn and the balance Mg. The T1 phase is a hexagonal crystal structure with lattice constants of a = 0.992-0.945 nm and c = 1.034-1.003 nm, which decrease with the increase of Zn content in T1 phase. Compound T2 is also hexagonal with 26.4% -28.4% Mg, 63.2% -65.5% Zn and 7.1% -8.4% Ca. At 300 ° C, the solubility of Zn in Mg-based solid solutions increases with the addition of Ca, with a maximum solubility of 3.7%. In the Mg-rich region of the phase diagram of 300 ° C isothermal phase in Mg-Zn-Ca system, there are three phases of α-Mg + Mg2Ca + T1, α-Mg + T1 + T2, α-Mg + T2 + MgZn and MgZn + T2 + Mg2Zn3.