Kiyoshi Aoki1 and Osamu Izumi1
1The Research Institute for Iron, Steel and Other Metals, Tohoku University, Sendai
The room temperature ductility of the L12 type intermetallic compound Ni3Al which has been accepted to be brittle so far was improved considerably by a small addition of boron. Binary Ni3Al poly-crystals without boron did not exhibit any ductility at room temperature in agreement with previous reports, while those to which boron was added showed considerable ductility as determined from the bending, cold-rolling and tensile tests. Improvement of the room temperature ductility by boron addition did not bring about lowering of the yield strength of Ni3Al. Fracture mode changes trom the intergranular one which is typical for the alloy without boron to the transgranular type in the alloys containing a small amount of boron. Boron appeared to be the effective element which suppress the intergranular fracture. The mechanism of the improvement of the room temperature ductility was discussed based on impurity segregation to grain boundaries or the peculiarity of the grain boundary structure.
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