Dr. Michael J. Zehetbauer

Abstract:

Score I: Consolidation Of Ti And Ti-6Al-4V-Chips Achieving Bulk Nanomaterials [1]. The two most important Severe Plastic Deformation (SPD) methods [2] - Equal Channel Angular Pressing (ECAP) and High Pressure Torsion (HPT) - were used for recycling and/or upcycling of titanium chips. To check the quality of the consolidated materials, results of mechanical testing, texture analysis, and of optical and electron microscopy were compared with those of the bulk counterparts. It is concluded that full consolidation i.e. the recycling of chips using SPD is possible at temperatures which not only are significantly lower than those of melting but also than those of sintering while reaching the same density. However,  the chips must be prevented from mutual sliding as plastic deformation is essential for successful consolidation. Still, small sizes of chips, enhanced pressures, as well as elevated temperatures prove as beneficial to successful for consolidation.

Score II: Effect Of High Pressure Torsion On The Magnetic Properties Of Two Fe-Based Metallic Glasses. Recently, High Pressure Torsion (HPT) was applied not only for achieving massive samples out of Fe-based metallic glasses but also for their crystallization [3,4], in order to increase the saturation magnetization. Magnetic measurements by means of Vibrating Sample Magnetometry (VSM) of the two Fe-based metallic glasses Vitroperm Fe_73.9Cu₁Nb₃Si_15.5B_6.6 and Makino Fe_81.2Co₄Si_0.5B_9.5P₄Cu_0.8 were undertaken. In contrast to the Vitroperm alloy, the Makino alloy showed – after applying at least 4 turns of HPT - an increase of magnetization by 10%, and a complete removal of HPT-induced increase of the coercivity related to deformation induced internal stresses. These effects occurred strictly in parallel to a HPT-induced crystallization which was not observed in the Vitroperm alloy [5]. It can be concluded that SPD processing of soft magnetic amorphous alloys appears as a viable alternative to the addition of nanocrystallizing elements, at least unless the material specific crystal systems are too complex to enable SPD induced crystallization [5].