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 铝硅合金经硝酸、氢氟酸出光后，形成了基体晶界和晶粒两部分，文章用扫描电镜观察了这两部分锌晶粒的生长过程，用能谱仪测试了浸锌层的组成；对比了不同浸锌温度锌晶粒的形貌。结果表明，锌晶粒优先在晶界处的腐蚀坑边缘、近晶界处、基体晶粒的孔洞边缘及晶粒内高活性点区域生长，并由腐蚀坑、孔洞边缘向周围及由近晶界处向基体晶粒中心扩散，直至布满大部分基体；浸锌初期发现锌晶粒之间有晶须生成。随浸锌温度的升高，锌晶粒逐渐长大，并由粒状转变为片状。

Microstructure Evolution of Al-Si Alloy(A356) During Zinc Immersion Process

Al-Si alloy consisted of the grain boundary of the matrix and the grains after corroding with nitric acid and hydrofluoric acid. The growing process of Zn grains was observed using scanning electron microscope(SEM) and composition of Zn coating was measured by energy dispersive analysis of X-rays(EDAX);the morphologies of Zn grains were compared at different zinc immersion temperature.The results showed that Zn grains grew in priority at the edge of etch pits,near grain boundary,at the edge of pores in the matrix and high activity area inside the grains,and that they diffused from the etch pits,the edge of pores to the surrounding region as well as the center of the grains,until they took up most of the matrix.It was found that the whiskers are formed between the grains in early stages of zinc immersion.Zn grains grew gradually and its morphology transformed from graininess to lamellae with the temperature increasing.