【摘要】 研究了定向凝固NiAl Mo(Hf)和NiAl Fe(Nb)合金的拉伸行为和显微组织变化。结果表明 ,两种合金在一定的拉伸条件下均具有反常的屈服行为和中温脆性。反常屈服和中温脆性行为与合金中含有的Ni3Al相有关。两种合金在高温时还表现出高应变速率的超塑性变形行为。超塑性变形的主要机理是位错滑移和攀移产生的应变硬化与动态回复和动态再结晶的应变软化作用相平衡。超塑性变形试样的断口呈韧性特征 ,在断裂区有孔洞产生。更多还原

【Abstract】 The microstructure change and tensile behavior of directionally solidified NiAl-Mo（Hf） and NiAl-Fe（Nb） alloys have been investigated. The results show that the anomalous yield behavior and intermediate temperature brittleness of the alloys are related to the Ni₃Al phase. Both of the alloys exhibit high strain rate superplastic behavior at elevated temperature. The main deformation mechanism of superplasticity is the balance between strain hardening. After the superplastic deformation, the fracture surfaces appear to be ductile, and the fracture regions contain cavities.更多还原