Thermal expansion and structural relaxation of microcrystalline and amorphous Ni-P alloys

Abstract

Continuing former investigations on Co-P and Fe-P, the changes in length of Ni100 − xPx samples (8 ≤ x ≤ 24, x 20 totally amorphous) on continuous heating and on step-annealing were measured. As long as structural relaxation has not completed, reversible thermal expansion competes with irreversible shrinkage. This effect is considerably stronger than that observed on Co-P but nearly as large as in Fe-P. Therefore it is not directly determined by short-range order which is similar to that of Co-P but not to that of Fe-P. On the other hand, the reversible thermal expansion coefficient and its composition dependence exhibit a clear correlation with short-range order and reflect especially the peculiar structural properties of Fe-P alloys.