SOME OBSERVATIONS ON DEFORMATION CHARACTERISTICS OF BULK POLYCRYSTALLINE ZIRCONIUM HYDRIDES .1. DEFORMATION AND FRACTURE OF HYDRIDES BASED ON GAMMA-PHASE

The deformation behaviour of bulk polycrystalline zirconium hydrides in the composition range ZrH1.27 to ZrH1.66 has been investigated by compressive loading at temperatures between room temperature and ∼500° C. Single-phase δ-zirconium hydride is brittle below ∼ 100° C. Analyses of slip traces on δ specimens deformed at temperatures between ∼ 100 and ∼ 250° C have shown that the glide planes are {111} types. The deformation characteristics of δ and (δ + γ) alloys at temperatures between ∼ 100 and ∼ 500° C are consistent with the hydrogen vacancies in the δ-phase providing significant lattice friction to the movement of dislocations in the zirconium lattice of the hydride structure. The room temperature fracture stress of (δ + γ) alloys increases with the volume fraction of the γ-phase and this can be related to the resistance offered by γ platelets to the propagation of cleavage cracks in the δ matrix. In a (δ + γ + α) alloy the resistance to crack propagation at room temperature is further increased by the soft α-zirconium phase. © 1969 Chapman and Hall.