Effect of Multi-Elements Substitution on the Mechanical Properties of Intermetallic Compound
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MRS Advances © 2019 Materials Research Society DOI: 10.1557/adv.2019.119
Effect of Multi-Elements Substitution on the Mechanical Properties of Intermetallic Compound Syuki Yamanaka1, Ken-ichi Ikeda2, Seiji Miura2 1 Graduate student, Department of Materials Science and Engineering, Hokkaido University, Kita13 Nishi 8, Kita-ku, Sapporo 060-8628, Japan
2 Division of Materials Science and Engineering, Faculty of Engineering, Hokkaido University, Kita13 Nishi 8, Kita-ku, Sapporo 060-8628, Japan
ABSTRACT
It is well known that various elements substitute for a certain sub-lattice of intermetallic compounds. There have been various experimental investigations of the effects of substituted elements on mechanical properties, however, there are few reports describing the effects of multi-element substitution. In the present study, L12-type compounds A3B (Ni3Al and Co3(Al,W)) were selected as model compounds because their substitution behavior is well known. It was reported that various elements such as Ni, Co, Cu, Pd and Pt occupy the A-site, whereas Al, Si, Ga, Ge, Ti, V, Nb, Ta, Mo, and W occupy the B-site. These elements are expected to introduce local lattice distortion, which may affect the motion of dislocations over a wide range of temperatures. Several alloys composed of five or more elements including Ni, Co, Al, Mo, and W, were prepared using an Ar-arc melting machine and heat-treated. Several alloys were found to include an (Ni, Co)3(Al, Mo, W, …)-L12 compound as a constituent phase. The nano-hardness of these L12 phases was higher than that of the high-strength Co3(Al,W)-L12 compound, confirming that multi-element substitution is an effective way to improve the mechanical properties of an intermetallic compound without decreasing the phase stability.
INTRODUCTION Intermetallic compounds have attracted recent attention after the successful utilization of TiAl as the base material for structural applications in jet engines. Conventional intermetallic compounds such as Ni3Al are still attractive for structural use as precipitates in the Ni solid solution matrix. It is well known that many elements
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substitute preferentially into a particular sub-lattice in intermetallic compounds. For example, it is well known that Co, Pd, and Pt substitute for the A-site (Ni-site), whereas W, Si, Ga, Ge, Ti, Mo, and Ta substitute for the B-site (Al-site) in Ni3Al [1]. These elements substitute for a certain constituent element (Ni or Al) because they have similar bonding characteristics with the counterpart element in another site (Al or Ni). Intermetallic compounds are expected to provide the possibility of unique alloy design due to such substitution behavior, but the mechanical properties and phase stability after substition with many elements are not well understood. Once an element occupies a p
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