Plasticity in 18R Cu-Zn-Al single crystals: temperature and strain-rate dependence

摘要

Single crystals of 18R Cu-Zn-Al martensite with long-range order (LRO) were deformed in compression to investigate the temperature and the strain-rate dependences of the yield stress. The yield stress show a positive temperature dependence between 293 and 523 K and a negative strain-rate sensitivity is measured above about 340 K; only one close-packed slip system is observed, equivalent to (111) [110] of Ll(2) superlattices. The influence of different dislocation pinning mechanisms proposed for LRO alloys is analysed and a diffusive strengthening mechanism is considered. A thermal activation model is developed on the basis of dynamic strain-ageing theories. [References: 27]