AN X-RAY DIFFRACTION TOPOGRAPHIC METHOD AND ITS APPLICATION TO FRACTURE PROBLEM OF METAL

A new X-ray diffraction topographic method was developed and used to study the fracture morphology and process in three point bending test of Mo single crystals. It was shown that not only the different regions similar to ones of optical fractograph, namely, unstable and stable extension regions, as well as triangle region formed by tearing, but also the different orientated subgrains, subgrains' rupture and their stress states may be revealed from the X-ray diffraction pattern. By the fracture process investigation, the subgrain rotation, the lattice bending and the spreading of plastic zone were found in front of the precracks.