in-situ法Cu-Nb多芯線材の室温における疲労強度

In order to investigate fatigue strength and fracture mechanisms of Cu-Nb composite multistrand wires, fatigue tests at room temperature and fractographic observations were carried out using Cu-20, -30, and -40wt%Nb composite wires fabricated by in-situ processing. Fatigue strength in the high cycle region increases significantly as the content of Nb increases, as in the case of U.T.S., while the strength in the low cycle fatigue region is the lowest in Cu-30wt%Nb wire, as in the case of 0.2% proof stress. Fractographic observations revealed that slip plane decohesion facets and inclusions within the Cu wire sheath were possible sites for the crack initiation. Evidence on the roles of the Nb filaments and Cu-Nb filaments acting as barriers against crack propagation was obtained by observations of the longitudinal section of fatigued specimens.