Insight into the Role and Mechanism of Nano MgO on the Hot Compressive Deformation Behavior of Mg-Zn-Ca Alloys

Abstract

Aiming to investigate the role and mechanism of nano MgO on the hot compressive deformation behavior of Mg alloys, the Mg-3Zn-0.2Ca alloy (MZC, in wt%) and the 0.2MgO/Mg-3Zn-0.2Ca alloy (MZCM, in wt%) were investigated systematically in the temperature range of 523–673 K and the strain rate range of 0.001–1 s−1. MZCM shows finer grains and second phase because of the refinement effects of added MgO. Flow behavior analysis shows that the addition of nano MgO promotes the dynamic recrystallization (DRX) of MZC. The flow stress of MZCM is lower than that of MZC during deformation at 523–623 K but exhibits a reverse trend at 673 K and 0.1–1 s−1. The constitutive analysis indicates that dislocation climb is the dominant deformation mechanism for MZC and MZCM. The addition of nano MgO particles decreases the stress sensitivity and deformation resistance for thermal deformation and improves the plasticity of the MZC. Besides, according to the processing map constructed at strains of 0.7 and corresponding microstructure evolution, MZCM exhibits higher power dissipation efficiency and smaller instability regions than MZC, and the optimum hot working condition for MZCM was determined to be at 623–653 K and 0.01–0.001 s−1.

Hot Deformation Behavior and Constitutive Analysis of As-Extruded Mg–6Zn–5Ca–3Ce Alloy Fabricated by Rapid Solidification

“…In accordance with Equations ( 5) and ( 6 Because there are three variations in Equation ( 4), by calculating partial differential for temperature and strain rate, respectively, the linear relationship of ln[sinh(ασ)] − 1000 ε − ln[sinh(ασ)] is 3.68. Accordingly, the current activation energy, Q, is estimated to be 186.3 kJ/mol, which is higher than that of the self-diffusion in pure Mg. Zheng et al [29] researched the effect of the addition of MgO on the plastic deformation behavior of Mg alloy and indicated that the lower activation energy (150.3 kJ/mol) can be attribute to the fine grains and second phases. In this study, the moderate Q value can be attributed to the exceptional fine grain size and the occurrence of numerous second phases, such as Mg 2 Ca and Mg-Zn-Ce phases (T' phase).…”

Mg-Ca0.3 Electrochemical Activity Exposed to Hank’s Physiological Solution and Properties of Ag-Nano-Particles Deposits

“…The microstructure of Mg-Ca alloys systems includes α-Mg (hexagonal crystalline structure) and Mg 2 Ca phase, in which crystalline cell presents double parameter values (a = 0.623, c = 0.1012) compared to those of Mg [55][56][57][58]. The standard electrode potential of Ca is more negative (−2.87 V SHE ) than that of Mg and it may be assumed that Ca 2+ will be released, originating from the Mg 2 Ca particles, considered as an anodic active [54,[59][60][61][62][63].…”