原子力システム用超耐熱モリブデン基合金の設計

Abstract

Mo-based alloys are promising the candidate materials for structural applications in the advanced nuclear power system. In order to obtain some indication for the alloy design, the high-temperature tensile strength, high-temperature creep strength, corrosion resistance to liquid metal and alloy density were investigated system atically in this study.The high-temperature micro-hardness was measured with binary, ternary and some multi-components alloys, and found to be predictable using the differences in atomic radius and in Young’s modulus between the Mo atom and the alloying element. The high temperature tensile strength was also predictable from the calculated micro-hardness of alloys. The melting temperature which was associated with the high temperature creep strength, was shown to be predicted by the d-electron parameters calculated by the DV-Xα cluster method. The corrosion resistance in liquid sodium was found to be significantly higher for the Mo-based alloys than for Nb-based alloys. In addition, the alloy densities could be estimated readily by taking the compositional average of each densities for constituent metals in alloys.Based on these results, a Mo-Re-W-Zr system was selected as the most promising system, and its properties were estimated with varying alloy compositions. It was concluded that the present predicting method of alloy properties indeed provided a good indication for the efficient alloy design of Mo-based alloys.