Papers by Author: Hans Joachim Bunge

Abstract: The new developed “sweeping detector” techniques using high energy synchrotron radiation allow to measure textures and microstructures of materials and their change during heat treatment with high location and orientation resolution. Here we show these new methods applied to cold rolled and subsequently annealed nickel samples. The grain-resolved measurements show, impressively, many details of the recrystallization process which can otherwise not be seen. The results of these measurements can be the base for omprehensive recrystallization theories.

Abstract: The substructure nonuniformity of metal materials with developed deformation texture was studied by use of the X-ray method of Generalized Pole Figures. Main regularities of substructure nonuniformity were revealed for the first time. Substructure conditions of grains in rolled material form an extremely wide spectrum and vary by passing from texture maxima to texture minima, where residual deformation effects are most significant. The distribution of residual elastic microstrains in the orientational space of rolled material shows the distinct cross-wise system, consisting in alternation of quadrants with predominant microstrains of opposite signs.

Abstract: The substructure inhomogeneity of rolled Ti-48%Ni-2%Fe single crystals was studied by the X-ray method of Generalized Pole Figures. Under rolling of single crystals, along with texture formation, the nonuniform substructure develops. It is conditioned by inhomogeneous reorientation of the crystalline lattice and local differences in predominant plastic deformation mechanisms. The distribution of residual deformation effects is controlled by the orientation of separate regions relative to texture maxima. Rolled single crystals prove to be divided into subcomponents with close orientations and opposite signs of elastic microstrains.

Abstract: Additional to the position of any volume element of a (poly)-crystalline material its crystal orientation must also be known. Both together are described in the six-dimensional orientation-location space. The paper describes the most frequent structures of materials in this space and how these can be imaged with the "Moving Area Detector Method" using hard synchrotron X-rays. This technique is equally well suited for basic reseach in materials science as well as for non-destructive testing of technological parts or even complex structural components.

Abstract: The newly developed “sweeping detector” technique with high energy synchrotron radiation allows to measure textures and microstructures of materials with high location and orientation resolution. This method was applied to hot rolled aluminium manganese alloys and to rolled nickel samples in different recrystallization stages. The grain-resolved measurements show, impressively, many details of the recrystallization process which can otherwise not be seen. That can be the base for comprehensive recrystallization theories.