Improvement of Room Temperature Ductility of Stoichiometric Ni3Al by Unidirectional Solidification.

概要

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One of the authors has reported that unidirectional solidification by a floating zone method (FZ-UDS) is effective in improving the room temperature ductility of polycrystalline Ni3Al without ductility enhancing elements (Acta Metall. Mater., 38 (1990), 2667). More details on the microstructure and mechanical properties of the stoichiometric Ni3Al grown by FZ-UDS were investigated in this paper. The solidification structure was dependent on the growth rate. The alloys showed a columnar grained and single phase structure with weak ‹100›, ‹110›, or ‹210› texture when the growth rate was above 13 mm/hr, and showed a large tensile elongation of more than 60% at room temperature. Crystallographic slip and transgranular fracture were observed on the fracture surface. Intergranular fracture was completely suppressed. When the growth rate was below than 13 mm/hr, the alloys precipitated martensitic second phases in the columnar grained Ni3Al matrix and showed a smaller tensile elongation than that of the alloys grown at the growth rate of 24 mm/hr. These results indicate that the FZ-UDS is a promising method to improve the room temperature ductility of polycrystalline Ni3Al.
The Iron and Steel Institute of Japanの論文