Al-7.5Zn-1.6Mg-1.4Cu合金的均匀化处理

Homogenizing Treatment of Al-7.5Zn-1.6Mg-1.4Cu Alloy

利用光学显微镜、扫描电镜、能谱分析、X射线衍射分析和差示扫描量热分析等研究了Al-7.5Zn-1.6Mg-1.4Cu合金铸态与均匀化态的显微组织演化与元素分布,确定了该合金的均匀化温度与过烧温度。结果表明,合金铸态组织中存在严重的枝晶偏析,经470℃保温24h后,枝晶网络变稀,共晶相与η相回溶至基体,偏析基本消除。470℃保温24h是该合金较为理想的均匀化工艺。

The microstructures evolution of as-cast and homogenized A1-7.5Zn-1.6Mg-1.4Cu alloy were studied by means of optical microscope, scanning electron microscope, energy dispersive spectrometer, X-ray diffraction, and differential scanning calorimeter. The homogenizing and overburnt temperatures of the alloy were determined. The result showed that severe dendritic-segregation existed in its as-cast structures. After 24 h homogenization at 470 ℃, segregation was almost eliminated while eutectic network became sparse and lamellar eutectic and η phase dissolved into the matrix. The appropriate homogenizing process for the alloy was 470 ℃/24 h.