合金元素Zr韧化不同计量比Ni3Al合金的微观机制

利用正电子湮没技术（PAT）测量了不同化学计量比二元Ni3₃Al合金及不同Zr含 量Ni3₃Al合金的正电子寿命谱，并估算了合金基体和晶界缺陷处的自由电子密度.结果表明，二元Ni77₇₇Al23₂₃合金的基体和缺陷态的自由电子密度都比二元 Ni74₇₄Al26₂₆合金的高. Ni3₃Al合金晶界缺陷处开空间大于Ni空位或Al空位的开空间，晶界缺 陷处的自 关键词： 3Al合金')" href="#">Ni3₃Al合金 微观机制 自由电子密度 韧化

The micromechanism of alloying element Zr affecting the ductility of Ni33Al alloy with different Al contents

Positron lifetime parameters have been measured by position annihilation technique in binary Ni77₇₇Al23₂₃ and Ni74₇₄ Al26₂₆ alloys with different Al contents and Ni3₃Al alloy doped with different amounts of Zr. The density o f free electrons in bulk materials and grain boundaries was calculated in this p aper. The results show that the density of free electrons in bulk materials and grain boundaries in Ni74₇₄Al26₂₆ alloy is lower t han that in Ni77₇₇Al23₂₃ alloy. The open volume in grain boundary is larger in Ni74₇₄Al26₂₆ alloy, and the cohesion of grain boundaries is weaker. When an amount of Zr atoms is added into the Ni3₃Al alloy, they increase the density of f ree electr ons in the bulk and thus increase the bonding cohesion in the bulk. The other Z r atoms will segregate at grain boundaries and increase their free electron dens ity; this will strengthen the bonding cohesion in grain boundaries. Alloying ele ment Zr is found to be beneficial to reduce the brittleness of Ni3₃Al alloy with different Al contents.