B添加およびB 無添加の直方晶（O+α2）型Ti–27.5Nb–13Al合金の高サイクル疲労・超高サイクル疲労および（α+β）型Ti合金と比較した疲労ストライエーション解析
(High Cycle Fatigue and Very High Cycle Fatigue of Orthorhombic (O + α₂)-Type Ti-27.5Nb-13Al Alloy with and without B and Fatigue Striation Analysis in Comparison with (α + β)-Type Titanium Alloys)