Porous materials have received extensive attention for energy absorption in the last few years. In terms of this study, austenitic TRIP-steel/Mg-PSZ-composite honeycomb structures are formed with different mixing proportions due to ceramic extrusion at room temperature. Their specific energy absorption SEA as well as their compression strength have been registered as a function of the compressive strain. X-ray diffractometry (XRD), electron backscatter diffraction (EBSD) as well as electron dispersive X-ray (EDX) analysis support the microstructure characterization. The zirconia addition has mainly contributed as a hard phase in a ductile TRIP steel matrix and has reinforced the composite material up to a compressive strain of about 24%.

Abstract.A new generation of high alloyed cast CrMnNi-TRIP-steels was developed exhibiting high strength (UTS) as well as high uniform elongation for a maximum of energy-absorption. The nature of the high elongation is the formation of -martensite in the most deformed areas of the metastable austenitic steel, so that necking is delayed. Because of the low stacking fault energy, due to the high alloying concept, deformation is mainly accompanied by the development of deformation bands in coarse austenitic grains and further the -martensite. Within this study, stress-strain curves will be evaluated by the corresponding microstructure information obtained by LOM, SEM and EBSD examinations. The formation of -martensite is discussed for tensile and compressive loading at room temperature. The arrangement of martensite within the microstructure and the local deformation dependency of the -martensite fraction is considered. Martensite kinetics will be presented for interrupted deformation tests, determined via magnetic balance (MS), EBSD and light optical metallography (LOM).

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Magnetization measurements of the hysteresis loop, M(B), of melt-textured Y1Ba2Cu3O7−δ (YBCO) crystallites were performed in external magnetic fields up to 10 T. The M(B) curves exhibit, between the superconducting transition temperature Tc and almost 39 K, a peak at a finite field B* which increases with decreasing temperature. The crystallites possess a high density of dislocations which could have been introduced during the high temperature treatment and/or by stresses created due to differences in the lattice parameter of small inclusions and the YBCO matrix. The large dislocation density together with the high sensitivity of the superconducting order parameter on deviations from the regular crystal structure and the small coherence length are suggested to be responsible for the observed fishtail shape of the magnetization curves.