MA法によるNiアルミナイドの製造とその機械的性質 (金属間化合物の粉末冶金プロセスと特性<特集>)

概要

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As representative Ni aluminides, NiaA1 (26, 27at%Al), NiiAl+NiAl (32, 38at%Al) and NiAl (42, 46at%Al) intermetallic compounds were produced by mechanical alloying (MA) process for the purpose of refining microstructures. MA was performed in the attritor mill using pure nickel and NiAl prealloyed powders. MA treated powders were consolidated using the vacuum hot pressing. Produced aluminides showed fine grain microstructures with average grain size under 4 pm and had relative density above 97%. Each of them, however, contained a few percent of alumina which was made by oxidation of Al during MA treatment. This causes the decrease of Al content of at most 2 at%A1 compared with blend composition. High strengths over 1000 MPa and large fracture strain of more than 15% at room temperature were found for all of the alloys. Furthermore, it was confirmed that the flow stress of two phase alloy was larger than that of mono-phase alloys in the temperature range from room temperature to 1073K. The high strain rate sensitivity exponent (m value) of more than 0.3 was obtained for Ni3Al at 1073K and this is considered to be associated with the development of superplastic deformation.
社団法人粉体粉末冶金協会の論文