Thermal stability of hafnium bronze subjected to dynamic channel angular pressing

Abstract

Thermal stability of the structure of Cu-0.8%Hf alloy subjected to severe plastic deformation by 2 passes of dynamic channel angular pressing (DCAP) has been investigated. It is demonstrated that after such deformation the microstructure of the hafnium bronze is non-uniform, where areas of cell structure are neighboring with thin-lamellar structure of twinning type. Such structure indicates the action of two deformation mechanisms, dislocation sliding and twinning. It has been revealed that doping with hafnium has considerably affected susceptibility of copper to relaxation processes under the DCAP and following annealing. It has been found that the microstructure formed under the deformation can be retained at the annealing up to 500 C without noticeable changes, and the microhardness changes only slightly in this temperature range. At the same time, at heating up to 600 C and higher the relaxation processes are developed in the structure which is accompanied with a drastic drop of microhardness. © Published under licence by IOP Publishing Ltd.