Positron annihilation lifetime spectroscopy investigation of thermal aging effect for the mechanical properties of hydrogen-absorbed tantalum

水素吸収したTaの機械的特性に及ぼす熱時効影響の陽電子寿命測定による検討

石島 暖大 ; 横山 賢一*; 上野 文義  ; 阿部 仁 

Ishijima, Yasuhiro; Yokoyama, Kenichi*; Ueno, Fumiyoshi; Abe, Hitoshi

水素を吸収したタンタル(Ta)における空孔-水素クラスター生成の挙動と機械的特性に及ぼす熱時効の影響を、陽電子消滅寿命分光法(PALS)と引張試験によって調べた。PALSの結果から、200C以上の時効では815個の空孔を含む空孔クラスターが発生し、300Cの時効では3時間および6時間充電した試料で空孔-水素クラスターが発生した。また、これらの熱時効条件ではTaの熱時効による延性低下が確認された。これらの結果から、熱時効においてTaに固溶しているHは空孔-水素クラスターを生成し、変形時の転位移動を抑制することで、延性低下を引き起こしていることが推察された。

The effect of thermal aging on the behavior of vacancy-hydrogen (H) cluster generation and the mechanical properties of tantalum (Ta) were investigated by positron annihilation lifetime spectroscopy (PALS) and tensile tests. Based on the PALS results, vacancy clusters that included 8-15 vacancies were generated after aging at and above 200C, and vacancy-H clusters were generated in 3 and 6 h-charged specimens after aging at 300C. The loss of ductility in Ta and crack generation were observed by conducting tensile tests in 6 h H-charged specimens after aging at 200C for 2000 h and in 3 and 6 h H-charged specimens aged at 300C for 2000 h. The reduction of ductility due to thermal aging of Ta was also observed under these thermal aging conditions. These results suggested that vacancy-H cluster generated by dissolved H during thermal aging induced the ductility loss by reducing the dislocation migration during deformation.