铸造镁合金AZ91D金相腐蚀方法研究

Metallographic Etch for Cast AZ91D Magnesium Alloy

对砂型和金属型铸造AZ91D试样进行了铸态下与固溶处理后金相腐蚀研究,对压铸AZ91D试样进行铸态金相腐蚀和EBSD试验研究。结果表明,铸态砂型和金属型试样树枝晶形状显示六重对称性特征,一次枝晶间夹角为60°,固溶处理后晶粒尺寸变大。压铸试样冷却速度快,枝晶不能充分生长,难以显示六重对称性特征,EBSD试验能够准确测量压铸试样的晶粒尺寸和晶粒取向。

The metallographic etch for as-cast and solid solution treated samples of AZ91D magnesium alloy in sand casting and permanent mould casting has been performed,and as-cast microstructure and ESBD experiment of die casting AZ91D magnesium alloy have been investigated.The results show that the dendrites in as-cast microstructures of sand casting and permanent mold samples are characterized by sixtuple-symmetrical features,in which the angle between the primary dendrites is 60°,and the grain size can coarsen after solid solution.The absence of sixtuple-symmetrical features can be observed as a result of high cooling rate restraining the full growth of dendrites in die casting samples.EBSD experiment can accurately measure the grain size and grain orientation in die casting samples.