Author(s)

Maria Victoria Castro Riglos, Alfredo Tolley

División Física de Metales, Centro Atómico Bariloche, Comisión Nacional de Energía Atómica, San Carlos de Bariloche, Argentina.

The combined effect of micro-alloying with Si and Ge and/or plastic deformation prior to ageing at 160°C on age hardening has been studied in an Al-2 at% Cu alloy. The results obtained indicate that the hardness response is faster and the peak hardness is higher when plastic deformation and micro-alloying are applied together than performing each procedure individually. Different amounts of deformation, ranging from 0% to 30% have been utilized. An optimum deformation degree for the hardening response has been established around 8% for the Al-Cu-Si-Ge alloy. Characterization by transmission electron microscopy (TEM) shows that the peak hardness is due to a complex microstructure that contained θ" disc shaped precipitates, rod-shaped Si-Ge precipitates and θ' plates that were heterogeneously nucleated on the Si-Ge particles. Pre-deformation has been found to stimulate the growth of the θ' plates due to enhanced diffusion along dislocation cores. Increasing deformation reduces the influence of the Si-Ge precipitates on heterogeneous nucleation, leading to reduced peak hardness and faster over-ageing.

Al-Cu Based Alloys, Precipitation, Microstructure, Hardness, Transmission Electron Microscopy

Victoria Castro Riglos, M. and Tolley, A. (2018) Influence of Si and Ge Microalloying Additions and Plastic Deformation on Precipitation Processes in Al-Cu Based Alloys. Journal of Minerals and Materials Characterization and Engineering, 6, 356-372. doi: 10.4236/jmmce.2018.63025.