【摘要】 用光学显微镜、扫描电镜研究了Zn 5Al共晶合金超塑变形的表面效应及其影响因素。结果表明 :超塑变形中的晶界滑移机制导致某些晶界由材料内部滑移至表面 ,从而使外表面增加 ;Zn 5Al合金的超塑性表面流动具有长程性 ,而且表面流动对超塑变形具有协调作用 ;表面镀层由于破坏了表面流动的协调性 ,对合金的超塑变形产生阻碍作用。空洞是材料的内自由表面 ,其形核长大与 (2γs-γgb)有关 ,提高表面能、降低晶界能可增强材料的超塑性。更多还原

【Abstract】 The surface effect on superplasticity of Zn 5Al eutectic alloy has been studied with optical microscope and SEM. Investigation shows that some grain boundaries can move out from inside to the surface during superplastic deformation (SPD), which produces new surface of the specimen; surface flow of Zn 5Al alloy has chara cteristic of long distance and can coordinate SPD; electroplate impairs the superplasticity of the alloy because of its disturbing surface flow. Cavity is the inner surface of the alloy and its formation and growth relate with (2 γ s- γ gb ), increasing the surface energy or reducing grain boundary energy can enhance the superplasticity of the alloy.更多还原