应用正电子湮没技术定量估算高纯铁形变的位错密度和空位浓度

Estimation of dislocation density and vacancy concentration in deformed high purity iron using PAT

采用慢拉伸与多普勒展宽相结合．研究了单一试样以５×１０－５／ｓ的应变速率拉伸时，高纯铁形变作品５００Ｋ回复前后Ｓ参数随形变量的变化［Ｓ（ε）曲线］。实验结果表明．回复前的Ｓ（ε）曲线包含位错和空位的贡献．回复后仅食位错的贡献。对于同一形变量的样品．５００Ｋ回复后Ｓ参数下降．形变量越大下降量越大．对应空位贡献也越大：根据两态捕获模型计算可得：高纯铁拉伸变形产生空位和位错．空位浓度和位错密度均随形变量的增加而增加．空位浓度ＣＶ的数量级为１０１７－１０１９ｃｍ－３．位错密度ρｄ的数量级为１０９－１０１１ｃｍ－２．

Variation of S-parameter with the strain [S(ε)curves] under the strain rate of 5×10 5/s in high purity iron was investigated by Doppler broadening measurements combined with slow tensile tests. In order to estimate dislocation density pd and vacancy concentration Cv,the deformed samples were annealed at o00K for 10h to eliminate the effect of vacancies induced by the strain and to retain the strain induced dislocations.A calculation based on the trapping model gave the dislocation density ρd on the order of 109-1011cm2 and the vacancy concentration Cv.on the order of 1017-1019cm3.both of which were increased with the strain.