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.
Highlights
Research on magnesium (Mg) and its alloys as biodegradable implants has grown for years due to their biodegradability, biocompatibility and moderate mechanical properties close to those of bone [1].Aiming to further improve the bioactivity and mechanical properties of Mg alloys [2], Mg-matrix composites (MMCs) have been studied in the last decade
Compared with coarse in MZC (Figure 1a), finer and more uniform grains are observed in MZCM (Figure 1b)
(3) The constitutive equation of MZCM was developed; the n and m value show that dislocation climb is the dominate compressive deformation mechanism for MZC and MZCM, but the higher m value of MZCM might be attributed to the grain boundary sliding mechanism
Summary
Aiming to further improve the bioactivity and mechanical properties of Mg alloys [2], Mg-matrix composites (MMCs) have been studied in the last decade These materials use micro or nano-sized ceramic particles as reinforcements, such as calcium phosphate particles (CPP) [3], hydroxyapatite (HA) [4], tricalcium phosphate (β-TCP) [5], ZrO2 [6], Al2 O3 [7], ZnO [8] and TiB2 [9], which improve the yield strength (YS) and utimate tensile strength (UTS) of Mg alloys. Our previous research [11] shows that the orientation relationships of (111)MgO ~2.62◦ from (0002)α-Mg and [0-11]MgO//[-10]α-Mg were observed at the interface of Mg/MgO, which verified the excellent interfacial bonding, resulting in Metals 2020, 10, 1357; doi:10.3390/met10101357 www.mdpi.com/journal/metals
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