Hot deformation behaviors of titanium particles reinforced AZ91 composite

Titanium (Ti) particles reinforced AZ91 matrix composite (Tip/AZ91) was prepared by powder metallurgy method. In the present work, we investigated the hot deformation behavior of Tip/AZ91 composite by isothermal compression tests at a range of temperature from 250 degrees C to 400 degrees C and strain rates from 0.001 s(-1) to 1 s(-1). Microstructure observations revealed that Ti particles were distributed uniformly in the composite, with the presence of a diffusion layer containing Mg, Ti, and Al elements between the Ti particles and the magnesium (Mg) matrix. The strain-compensated Arrhenius constitutive model was con-structed, and the accuracy was evaluated by error analysis. The stress index exponent (n) was calculated as 4.98, indicating that the dislocation climb mechanism dominates the thermal deformation of Tip/AZ91 composite. Moreover, the calculated activation energy (Q) of 153.7 kJ/mol was observed to be lower than that of the pure AZ91 alloy, which can be attributed to the presence of a particle deformation zone (PDZ). Further microstructure analysis indicated that the continuous dynamic recrystallization mechanism (CDRX) occurred. As the recrystallized grains grow, the texture changes from a bimodal texture to a typical unimodal texture, resulting in a recrystallized < 0001 >//normal direction texture. In addition, the particle stimulated nucleation (PSN) phenomenon was observed around Ti particles at low Zener-Hollomon parameter (lnZ = 20.73) condition. (c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

A titanium particle-reinforced AZ91 matrix composite (Tip/AZ91) was prepared by powder metallurgy method. The hot deformation behavior of the Tip/AZ91 composite was investigated through isothermal compression tests. Microstructure observations showed a uniform distribution of titanium particles in the composite, with a diffusion layer containing magnesium, titanium, and aluminum elements between the particles and the magnesium matrix. The deformation mechanism was dominated by dislocation climb, and the presence of a particle deformation zone was observed.