不锈钢微裂纹形核扩展的TEM原位观察  

IN SITU TEM OBSERVATION OF NUCLEATING AND PROPAGATING OF MICROCRACKS IN STAINLESS STEEL UNDER TENSION

作　　者：李红旗[1] 陈奇志[1] 褚武扬[1] 

机构地区：[1]北京科技大学,北京科技大学材料物理系

出　　处：《金属学报》1996年第11期1159-1164,共6页Acta Metallurgica Sinica

基　　金：国家自然科学基金

摘　　要：３１０奥氏体不锈钢在透射电镜中的原位拉伸观察表明，如在裂尖发射位错后保持恒位移，则在裂尖能形成无位错区（ＤＦＺ）．这个弹性的ＤＦＺ不均匀减薄，其应力集中可等于原子键合力，从而导致纳米级微裂纹在ＤＦＺ中形核，并很快钝化成空洞．如果裂尖发射位错后继续拉伸，则上述基本过程被掩盖，仅看到交滑移使裂尖区减薄，从而导致微米级空洞或裂纹的形核和连接．如稍稍卸载，则可观察到裂尖前反塞积位错群的逆返现象．TEM in situ tensile tests of 310 stainless steel show that a dislocation free zone (DFZ) forms after equilibrium if the displacement keeps constant after many dislocations are emitted from a crack tip. The elastic DFZ is gradually thinned and the stress in DFZ will reach the cohesive strength resulting in nucleating of nanocracks in DFZ and blunting into voids. If continuously tensioning after crack tip emitted dislocations, and inhomogeneously thinning ahead of crack tip, then initiating and connecting of micro-voids(or micro-cracks) will be observed rather than DFZ, initiating of nanocracks and nanocracks' blunting into voids. The inversely piled-up dislocations ahead of a loaded crack tip can move towards the crack tip if unloading a little.

关 键 词：不锈钢 TEM 裂纹 形核扩展 微裂纹 

分 类 号：TG142.71[一般工业技术—材料科学与工程]