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Micro- and nanoindentation experiments were conducted to investigate the deformation mechanisms in a Fe79.4Cr13Mo5V1C1.6 (wt. %) cast alloy. This alloy consists of an as cast microstructure mainly composed of austenite, martensite, and a complex carbide network. During microhardness testing, metastable austenite transforms partially into martensite confirmed by electron backscatter diffraction. For nanoindentation tests, two different indenter geometries were applied (Berkovich and cube corner type). Load-displacement curves of nanoindentation in austenitic dendrites depicted pop-ins after transition into plastic deformation for both nanoindenters. Characterizations of the region beneath a nanoindent by transmission electron microscopy revealed a martensitic transformation as an activated deformation mechanism and suggest a correlation with the pop-in phenomena of the load-displacement curves. Furthermore, due to an inhomogeneous chemical composition within the austenitic dendrites, more stabilized region...

Fe-cladded MgB2 conductors have been prepared by the powder-in-tube method using mechanically alloyed nanocrystalline Mg+2B powder mixtures consisting of the constituents Mg, B, and MgB2 as precursor. Despite low Tc values of about 31 K, maximum critical current densities (Jc) of 22 and 7 kA/cm2 in external magnetic fields of 7.5 and 10 T, respectively, are achieved at 4.2 K. These excellent values can mainly be attributed to the very fine-grained microstructure of the superconducting phase. Higher values have only been reported for tapes doped with SiC nanoparticles. The irreversibility fields Hirr of these tapes are 9.5 and 4.2 T at 10 and 20 K, respectively.

Series of Pr–Co thin films have been prepared by pulsed laser deposition on Cr buffered MgO(100) substrate. The effect of deposition temperature for both buffer and Pr–Co layers on the phase formation, texture, and magnetic properties has been investigated. Unlike the buffer deposition temperature (TB), the Pr–Co deposition temperature (TD) has a large influence on the structure and magnetic properties of the thin films. For the extreme temperatures, i.e., 300 and 700°C, no Pr–Co phase formation is observed. However, films prepared between 300 and 700°C develop a hexagonal Pr–Co phase, identified by means of the (110) and (220) peaks observed in x-ray diffractometry. From pole figure measurements, the orientation relationship was determined to be Pr–Co(110)[001]‖Cr(100)[001]‖MgO(100)[001] and Pr–Co(110)[001]‖Cr(100)[011¯]‖MgO(100)[010]. Due to the fourfold symmetry of the MgO(100) substrate, the c axis is therefore found to be along both the MgO[010] and MgO[001] directions, which is also confirmed by mag...

The stress evolution during and after dc magnetron sputter deposition of Cu thin films with thicknesses of 20 and 300 nm and deposited with a constant rate of 0.1nm∕s onto Si (100) substrates is studied for various sputtering pressures (0.05–6 Pa). The stress was determined by means of in situ wafer curvature measurements using an optical two-beam deflection method. To correlate the stress evolution with the microstructure development, microstructure investigations were performed by scanning electron microscopy, atomic force microscopy, and electron backscatter diffraction. The results show the transition from tensile to compressive stress with decreasing sputtering pressure at different stages of the deposition. The features of the stress evolution during the early stage of deposition can be ascribed to the Volmer–Weber mechanism. For thicker films, three regions of the sputtering pressure can be distinguished concerning their effect on the stress evolution. The transition from compressive to tensile stress was correlated with the evolution from a dense to an open microstructure and with increasing surface roughness by increasing sputtering pressure. The results of the stress and microstructure evolution are interpreted in the context of the mechanisms being discussed in the literature.