Abstract Scope |
Refractory high-entropy alloys have attracted much attentions owing to their excellent properties, especially under elevated temperatures. However, defects such as high density, poor oxidation resistance and limited ductility hinder their further applications. Microalloying could be a therapy for those problems. VNbTiTaMoSi and MoNbTiSi and VNbTiTaSix systems are prepared and investigated on the phase formation and mechanical properties. Silicides are proved to be effective in improving the strength of RHEAs. VNbTiTaMoSi exhibits high yield strength of about 900MPa at 1200℃, which are higher than that of NbMoTaW and VNbMoTaW. Compared with B2 and Laves phase strengthened alloys, silicide strengthened alloys exhibit excellent combinations of ductility and yield strength at elevated temperatures owing to the limited solubility of silicon in refractory elements. Under tensile test, VNbTiTaSix exhibit brittle fracture characteristics. Through hot rolling, the silicides are broken and distribute discontinuously in ductile matrix, and the tensile ductility are greatly enhanced. |