抄録
The influence of different mixing methods of elemental powders on microstructures and mechanical properties of Ni-23. 9at%Al-0.5 at% B at elevated temperature was investigated. The main results obtained are summarized as follows;
1)Net mixing processed Ni3Al has much larger grain than dry mixing processed one by a factor of 7. This result suggests that dry mixing provides much more reactive sintering sites than wet mixing.
2)The room temperature yield strength of fine grained Ni3Al is about 720MPa and is roughly twice as strong as that of coarse grained one.
3) Ni3Al processed by both methods reveal a definite positive temperature dependence of hardness and yield strength to a peak temperature of 700K.
4)Yield point elongation can be seen clearly for fine grained Ni3Al. This is associated with the relief of expanded dislocations from Suzuki atmosphere.
5)Fracture mode of dry mixing processed Ni3Al is intergranual ductile at ambient temperatur and it replaces gradually intergranular brittle fracture with increasing temperature. On the other hand, fracture surface of wet processed one is trnsgranular ductile at ambient temperature and it replaces intergranular brittle fracture with increasing test temperature. It is found that transition temperature for wet mixing processed Ni3Al i s about 650K.
