Thermal stability and superplastic behaviour of an Al-Mg-Sc alloy processed by ECAP and HPT at different temperatures

7th International Conference on Nanomaterials by Severe Plastic Deformation

Pereira, P.H.R.^1,2 ; Huang, Y.^1 ; Langdon, T.G.^1

Materials Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton

SO17 1BJ, United Kingdom^1

CAPES Foundation, Ministry of Education of Brazil, Brasília, DF

70040-020, Brazil^2

关键词: Average grain size;    Elevated temperature;    Low angle grain boundaries;    Microhardness measurement;    Processed materials;    Processing condition;    Properties and microstructures;    Superplastic properties;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/194/1/012013/pdf
DOI  :  10.1088/1757-899X/194/1/012013

来源: IOP

【 摘 要 】

An Al-3%Mg-0.2%Sc alloy was processed by ECAP and HPT at different temperatures. Afterwards, samples subjected to 10 turns of HPT at 300 and 450 K, 8 passes of ECAP at 300 K and 10 passes of ECAP at 600 K were annealed for 1 hour at 523 K and their mechanical properties and microstructure were examined using microhardness measurements and EBSD analysis. In addition, tensile specimens with similar dimensions were machined from the HPT and ECAP-processed materials and further tensile tested at 523 K. The results demonstrate that the Al alloy processed by HPT at 450 K exhibits higher microhardness values (∼138 Hv) and a smaller average grain size (∼0.28 μm) after annealing at 523 K among all SPD processing conditions. Accordingly, the material subjected to HPT at an elevated temperature displays superior superplastic properties such that an elongation of ∼1020 % was attained after testing at 523 K at 1.0 × 10-3s-1. Furthermore, detailed EBSD analysis revealed a significant fraction of low-angle grain boundaries (LAGBs > 33 %) in the ECAP-processed material after annealing which may be responsible for the inferior superplastic behaviour by comparison with the HPT-processed samples (LAGBs