20钢渗硼过程中硼化物形核和生长的TEM观察及室温形变的影响

TEM OBSERVATION OF NUCLEATION AND GROWTH OF BORIDES DURING BORONIZATION OF STEEL 20 AND INFLUENCE OF PRIOR DEFORMATION

本文采用单向减薄制样法在透射电镜下直接观察了20钢渗硼初期硼化物的形核和生长特性及室温形变的影响。X射线及电子探针分析结果表明:渗硼初期试样表层仅有Fe_2B形成;表层硼原子浓度与形变量之间具有单调增长的关系;偏聚于位错胞壁之中的硼原子阻碍了形变组织的恢复和再结晶,加速了硼化物的形核和长大。

TEM observation in situ on the single-side thinned specimens wasmade of the nucleation and growth of borides during boronization of steel 20 andthe influence of prior room temperature deformation. The results of X-ray diffrac-tion and electron probe microstructure analysis show that only Fe_2B formed inthe surface layer of specimens at the beginning of boronization; the atomic concen-tration of B in the surface layer increased with the increase of deformation mon-otonously; and the segregation of B atoms in the dislocation cells hindered the re-covery and recrystallization of the deformed structure of the matrix and accelara-ted the nucleation and growth of borides in the surface layer.