Al-Zn-Cu系室温低Cu侧的相平衡关系

通过显微组织观察和X射线衍射分析,结合电子探针分析,确定了在Al Zn Cu系中所设计的14个不同成分的合金经充分成分均匀化和平衡阶梯冷却至20℃的合金相组成及成分·在其中11个合金中发现了T′相(Al4Cu3Zn)的存在,测定了4个合金中的T′相的成分,并得到了新的相平衡关系·从另一个侧面证实了T′相在室温时(20℃)是可以稳定存在的,同时说明美国金属学会1997年出版的相图集中的Al Zn Cu系20℃等温截面相图在低Cu侧的相关系上是不正确的·

Relationship Between Different Phase Equilibria of A1-Zn-Cu Alloys in Low-Copper Part at Room Temperature

The phase composition and relevant constituents of 14 different alloys designed for Al-Zn-Cu system were analyzed by means of microscopy, XRD and EPMA, which were all fully homogenized and evenly cooled step to step to 20°C. Among them the T' phase (A4Cu3Zn) was found in 11 alloys, then the composition of T' phases in 4 alloys were determined with the relationship between new phase equilibria. The results prove in another way that the T' phase may exist stably at room temperature, i.e., 20°C. In addition to the conclusion, it also indicates that the relationship between the phase equilibria low-copper part on the isothermal section diagrams at 20°C of Al-Zn-Cu alloys, which were shown in the collection of phase diagrams as published by ASM in 1997, is improper.