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Thermal Stability of an Mg–Nd Alloy Processed by High‐Pressure Torsion
Author(s) -
Tighiouaret Samia,
Lachhab Rabeb,
Hanna Abdelkader,
Azzeddine Hiba,
Huang Yi,
Baudin Thierry,
Helbert Anne-Laure,
Brisset François,
Bradai Djamel,
Langdon Terence G.
Publication year - 2019
Publication title -
advanced engineering materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 114
eISSN - 1527-2648
pISSN - 1438-1656
DOI - 10.1002/adem.201900801
Subject(s) - materials science , annealing (glass) , indentation hardness , grain growth , alloy , grain size , microstructure , electron backscatter diffraction , thermal stability , atmospheric temperature range , vickers hardness test , hardening (computing) , metallurgy , softening , composite material , thermodynamics , chemistry , physics , layer (electronics) , organic chemistry
The evolution of microstructure, texture, and mechanical properties of an Mg–1.43Nd (wt%) alloy is investigated after processing by high‐pressure torsion at room temperature through five turns and isochronal annealing for 1 h at 150, 250, 350, and 450 °C using electron backscatter diffraction and Vickers microhardness. The alloy exhibits a good thermal stability up to annealing at 250 °C, with mean grain size of ≈0.65 μm. The microhardness shows an initial hardening after annealing at 150 °C and then a subsequent softening. The deformation texture, a basal texture shifted 60° away from the shear direction (SD), is retained during annealing up to 250 °C. In contrast, a basal texture with symmetrical splitting toward SD is developed after annealing at 350 °C. The precipitation sequence and their pinning effects are responsible for the age‐hardening, stabilization of grain size, and the texture modification. The kinetics of grain growth in the Mg–1.43Nd alloy follows two stages depending on the temperature annealing range, with an activation energy of ≈26 kJ mol −1 in the low temperature range of 150–250 °C and ≈147 kJ mol −1 in the high temperature range of 250–450 °C.