摘要
理论计算得出:氢降低位错运动点阵阻力,使得裂尖释放位错临界应力强度因子降低;氢的存在使裂尖所释放的位错受到附加吸引力,缩短了 DFZ。TEM 原位拉伸实验表明(i)在氢气氛中,纯铁裂尖位错释放的临界应力强度因子降低。(ii)对 Fe-3%Si 单晶体,电解充氢后裂尖DFZ 消失。(iii)Fe-3%Si 多晶体预形变后充氢,裂尖存在 DFZ。实验结果证实了作者提出的理论模型。
Theoretical calculation indicates solute hydrogen makes the criti-cal stress intensity factor for dislocation emission from a crack tip decreaseddue to the reduction of the friction stress of lattice by hydrogen;Emittedfrom a crack tip,disilocation carries a fraction of hydrogen atoms gatheringthere and is exerted by an additional attractive force,which makes the DFZshort.TEM in-situ tensile experimental results show(1) the critical stressintensity factor for dislocation cmission was decreased when pure iron was ten-sioned in H_2 gas in environmental cell(2)no DFZ was observed for Fe-3%Si single crystal after hydrogen charging(3)a DFZ was present for polycrys-talline Fe-3% Si alloy with hydrogen charging after predeformation.All resul-ts demonstrate the theoretical model.
关键词
氢
裂尖
位错
临界应力
强度因子
DFZ(dislocation-free-zone)
hydrogen
CSIF(critical stress in-tensity factor)
