The changes of microstructures after the exhaustion of dislocation glide ability but before cracking, as well as microcrack initiation by them, were studied in detail byin-situ transmission electron microscopy (TEM) f...The changes of microstructures after the exhaustion of dislocation glide ability but before cracking, as well as microcrack initiation by them, were studied in detail byin-situ transmission electron microscopy (TEM) for pure copper, aluminum and iron. Thinning occurred in the thicker regions through dislocation gliding in the three metals. After that, {111} 〈112〉 twinning or tensile cracking took place in thinned zones in fcc metals. In the case of twinning, new microcracks were initiated along another {111} plane by the high stress concentration near the growing tip of the twin, while in iron (bcc), many nanocracks were initiated in the thinned areas just ahead of the crack front, resulting in misorientation microstructure from which microcracks or microvoids were developed.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 59471048, 59725104, 19891180).
文摘The changes of microstructures after the exhaustion of dislocation glide ability but before cracking, as well as microcrack initiation by them, were studied in detail byin-situ transmission electron microscopy (TEM) for pure copper, aluminum and iron. Thinning occurred in the thicker regions through dislocation gliding in the three metals. After that, {111} 〈112〉 twinning or tensile cracking took place in thinned zones in fcc metals. In the case of twinning, new microcracks were initiated along another {111} plane by the high stress concentration near the growing tip of the twin, while in iron (bcc), many nanocracks were initiated in the thinned areas just ahead of the crack front, resulting in misorientation microstructure from which microcracks or microvoids were developed.
