挤压铸造ZA27合金中的夹杂物分析

Analysis on Inclusions in Squeezing Casting ZA27 Alloy

利用光学金相显微镜(OM)、扫描电子显微镜(SEM)、能谱分析(EDS)和X射线衍射(XRD)等实验手段,对经铝钛硼和铝稀土变质处理后的ZA27合金中的夹杂物进行了分析。结果表明:在ZA27合金中,稀土元素和杂质Fe元素会偏聚在晶界处,并与Zn、Al、Cu等形成成分复杂的富稀土相和富铁相;富稀土相为多边形块状,含有大量的稀土元素,同时还含有Zn、Al和Cu,并可能含有Ti;富铁相大多为针状,少部分为小块状,由Zn、Al、Cu和Fe四种元素组成,不含稀土元素,且Fe的平均含量大于20%;大块状富稀土相和针状富铁相对锌合金基体有严重割裂作用,易导致微裂纹的形成和扩展。

Al-5Ti- 1B and RE were used in modification of the ZA27 alloy, and then the inclusions in the ZA27 alloy were studied, by using optical microscopic and SEM examination, energy spectrum analysis （EDS） and X-ray diffraction （XRD）. The results show that rare earth elements and Fe elements are segregated at the grain boundaries, and form complex compounds with Zn, A1 and Cu in ZA27 alloy. The compounds rich in rare earth are polygonal blocks, containing a large amount of rare earth elements, also containing Zn, A1 and Cu, and may contain Ti; the compounds rich in iron are mainly needles, and a few are small pieces, consists ofZn, Al, Cu and Fe, not containing rare earth elements, and the average content of Fe is more than 20wt.%. These intermetallic compounds have fragmentary effect on the body, easy to produce stress concentration, leading to formation of micro-cracks and extensions.