Elastic moduli of polycrystalline TiCr1.8 over the temperature range of 3-410 K

The elastic moduli of polycrystalline TiCr1.8 have been measured over the temperature range of 3-410 K using the technique of resonant ultrasound spectroscopy (RUS). The reported results are for the C15 Laves-phase structure. The measured moduli display a normal temperature dependence, approaching 0 K with zero slope and decreasing linearly with increasing temperature at the higher temperatures. The Debye temperature, calculated from the measured moduli, was found to be 500 K. This material can absorb considerable amounts of hydrogen, but is unstable at ambient temperatures. The TiCr1.8-H2 system has a relatively low critical temperature, Tc, which has previously enabled thermodynamic measurements to be made above Tc. An elastic energy contribution to the enthalpy of formation has been calculated from the present measurements and compared to the thermodynamic results. The comparison suggests that the electronic contribution to the enthalpy of formation is comparable in magnitude to the elastic contribution, but opposite in sign