The effect of nano β-TCP on hot compression deformation behavior and microstructure evolution of the biomedical Mg-Zn-Zr alloy

Aiming to investigate the effects of nano beta-tricalcium phosphate (beta-TCP) on the hot deformation mechanism of Mg-Zn-Zr alloy (MZZ) and confirm the optimum hot working conditions of 2 beta-TCP/Mg-3Zn-0.8Zr composites (MZZT), thermal simulation test at deformation temperature and strain rate in the range of 523-673 K and 0.001-1 s(-1) was performed on MZZ and MZZT by using Gleeble-1500 simulator. The results of strain-stress behavior indicated that the flow stress of MZZT is higher than that of MZZ under the same hot deformation condition in the deformation temperature range of 523-623 K, whereas this trend opposed when specimens deformed at 673 K. Based on the establishment of constitutive equation, the average activation energy of MZZT for hot deformation is calculated to be 184.1 kJ/mol, and almost 60 kJ/mol higher than that of MZZ which can be attributed to the increasing of deformation resistance after the addition of beta-TCP particles. Furthermore, according to the processing map constructed at strains of 0.8 and microstructure observation, the optimum hot working condition for MZZT with higher value of power dissipation (37%) is determined to be 600-645 K and 0.01-0.001 s(-1).