采用变截面形状的坩埚,研究DZ417G高温合金在不同拉速下定向凝固组织的变化情况,发现在低于150μm/s的拉速下,变截面对凝固组织影响很小,凝固组织生长具有良好的延续性,变截面处杂晶的形成起源于小截面段枝晶尖端破碎从而产生杂晶,截面变大时促进了杂晶的生长；在250 μm/s的拉速下,变截面处存在足够大的横向温度梯度,凝固组织在变截面处产生杂晶.
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