Hot deformation behavior and workability characteristics of AZ91 magnesium alloy powder compacts—A study using processing map

Abstract

This study examined the hot deformation behavior and workability characteristics of AZ91 Mg alloy powder compacts by performing hot compression tests with a Gleeble 3800 machine. To this end, powder compacts with a relative green density of 93% were hot-compressed at temperatures ranging from 150 1Cto5001C and at true strain rates ranging from 0.001 s −1 to 10 s −1 . The true stress-true strain curves peaked at low strains, after which the flow stress increased slightly or remained constant. The work hardening rate decreased with increasing deformation temperature or strain rate. Processing maps were developed for all of the hot compression tests at strains of 0.1, 0.5, and 0.8, which represented a safe deformation domain at deformation temperatures and strain rates in the ranges of 150-300 1C and 0.001-0.01 s −1 . Kinetic analysis of the flow stress data for the safe deformation domain yielded an activation energy of 75 kJ/mol which is lower than those previously reported for the hot compression of bulk AZ91 Mg alloy. According to the developed processing maps and the microstructures of the hot-compressed specimens, the optimum hot working window for AZ91 Mg alloy powder compacts was determined to lie between 275-325 1C and 0.001-0.01 s −1 .

Hot Deformation Behavior and Constitutive Model of AZ80–0.8wt%Y Considering the Compensation of Strain

“…That is because Al atoms can lead to a strong dragging effect on the dislocations which can reduce the mobility of dislocations, thereby making the deformation harder [ 36 ] and increasing the Q value. [ 37 ] The Q‐value in the AZ80 is about 190 kJ mol −1 [ 20,38 ] much higher than AZ80‐0.8wt%Y in this study. Adding yttrium to magnesium alloy can form Al 2 Y phase which reduces the continuous distribution of eutectic Mg 17 Al 12 phase.…”

Hot Deformation Behavior and Processing Maps of SiC Nanoparticles and Second Phase Synergistically Reinforced Magnesium Matrix Composites

“…Figure 15 shows the safe area of different materials at strain of 0.5. It can be found that the workability region for the AZ91 alloy powder compacts is different from that of the commercial AZ91 alloy fabricated by die casting [26], which proves that forming conditions can affect the distribution of the processing map. Compared with the bimodal sized SiCp/AZ91 composite [10], the deformation temperature corresponding to the workability region of the coarse-grained nanocomposite is higher, which may be caused by the difference in grain size.…”