The incoherent spinodals of hydrogen in Nb,Ta and V

The incoherent spinodals for H in Nb, Ta and V are measured for wire-shaped specimens using the Gorsky effect, and compared with incoherent spinodals as deduced from solubility experiments. For Nb the spinodal touches the phase boundary at the critical point, whereas for Ta and V the maxima of the spinodals are about 100° below the phase boundary. Within the error bars the spinodals for Nb and Ta are isotope-independent.