Analysis of calorimetrically observed superconducting transition-temperature enhancement in Ti--Mo(5 at. %)-based alloys

The low temperature specific heats of four alloys based on Ti-Mo(5 at. percent) have been measured and analyzed. The four samples were (1) as-quenched with a β + ω structure, T/sub c/ < 1.50K, (2) compressively deformed with an α'' martensite structure, T/sub c/ = 3.20K, (3) solution strengthened by 1 percent Al addition with an α' martensite structure, T/sub c/ = 3.10K, and (4) solution strengthened by 3 percent Al addition with an α' martensite structure, T/sub c/ = 2.80K. The analysis employed a nonlinear fit for the usual parameters plus an asymmetric distribution of transition temperatures to account for the transition rounding. The procedure to be described yields accurate values for T/sub c/, and an equivalent (or homogeneous) specific-heat-jump height, ΔC, which is an indicator of the fraction of material participating in the superconductivity. These results combined with earlier observations indicate that the martensite phase, whether produced by deformation or otherwise, is the seat of an enhanced superconducting transition-temperature