Investigation of the special traits of failure of sintered iron by the in situ method

The method of studying processes of deformation and failure of powder materials in the column of a scanning electron microscope in situ is quite promising, and it is suitable for the further study of processes of failure. The specifies of the processes of deformation and failure of sintered iron manifests itself mostly at the structural level. Upon nucleation of a crack that is able to grow under the effect of applied stresses, the stage of formation of micropores and merger of microcracks does not play a substantial role. Cracks nucleate at places containing defects such as pores and particle boundaries. Primary cracks can nucleate independently of each other at places of increased stress concentration that is due to the inhomogeneity of the structure of sintered iron. A crack nucleated at the preceding stage of loading can be arrested, forming a stable defect during subsequent loading. This shows that porous iron is able to effect relaxational rearrangements in large volumes of material. The authors detected experimentally the rotation of individual particles during deformation, and that is direct proof of the substantial role of rotational modes in the deformation of porous bodies. The previously voiced assumption that the length of the slipmore » plane in sintered iron is limited by the dimension of the element of the structure bounded by intraparticular pores was experimentally confirmed.« less