α+β 型 Ti-(0～10)mass%V-(0.5～1)mass%O 合金の組織と機械的特性

抄録

  The microstructure and mechanical properties of the α+β type Ti-V-O alloys with high oxygen content were investigated. Ti-(0~10)mass%V-(0.5, 0.75, 1.0)mass%O alloy ingots were prepared using arc melting and hot rolling at 1373 K and 1073 K. The alloys were heat-treated at temperatures varying from 923 K to 1323 K for 3.6 ks under Ar flow. The β transus of the alloys was experimentally determined, and its value decreased with increasing V content and decreasing oxygen content in the alloy. Athermal ω was detected in the alloys with 6, 8 and 10 mass%V content and 0.5, 0.75 and 1 mass%O content after heat treatment at low temperatures in the range of 923 to 1123 K, wherein the V content in the β phase was higher than 12 mass%. The formation of the athermal ω led to the increase in hardness and decrease in the elongation and reduction of area of the alloys. Based on the investigation results, it was suggested that the Ti-4 mass%V-(0.5~0.75)mass%O alloy had an excellent balance between strength and ductility.