Robert John Zabala

Elastic moduli of polycrystalline, high-temperature binary intermetallic compounds

Abstract Ultrasonic measurements have been done of the elastic constants of a number of binary intermetallic compounds that melt above 1500°C. The data give directly the stiffness and specific stiffness of these materials and are expected to be indicators of their strength and specific strength.

Elastic moduli of polycrystalline, intermetallic compounds of titanium

Ultrasonic measurements have been done of the elastic constants of a number of Ti‐containing intermetallic compounds and two‐phase alloys that melt above 1400 °C. The data give directly the stiffness and specific stiffness of these materials and are expected to be indicators of their strength and specific strength. The data include Ti compounds with Cr, Ge, Re, Ru, and Sn and two‐phase systems consisting of Ti plus an intermetallic compound.

Melt-formed superconducting joints for Nb 3 Sn tape

Several new persistent-current superconducting magnet applications become possible for Nb3Sn when joints can be fabricated that are superconducting over the full range of temperatures and fields accessible with Nb3Sn. Melt forming has been found to be an effective way to form such a joint. Both tungsten inert gas welding and laser welding have been used successfully for this purpose. Methods for fabrication, microstructures, and performance of melt-formed Nb3Sn superconducting joints are discussed in detail.

Soft magnetic composites manufactured by warm co-extrusion of bulk metallic glass and steel powders

Soft magnetic composites of Fe-based bulk metallic glass and low-alloy steel have been manufactured by warm co-extrusion of precursor powders at temperatures within the supercooled liquid region of the glass. Composites were manufactured with amorphous volume fractions of 75%, 67%, and 100%. Full consolidation of the constituent powders was observed with the bulk metallic glass remaining substantially amorphous. The composite electrical resistivity was observed to be anisotropic with a resistivity of 79 μΩ cm measured transverse to the extrusion axis in a sample with 75% amorphous volume fraction. A 0-3 connectivity pattern with the low-resistivity steel phase embedded in a 3-dimensionally connected high-resistivity bulk metallic glass phase was observed with scanning electron microscopy. This confirms that the flow characteristics of the bulk metallic glass and the steel powders were comparable during extrusion at these temperatures. The saturation magnetization of 1.3 T was consistent with the volume we...