Bending properties of extruded AZ91-0.9Ca-0.6Y alloy and their improvement through precompression and annealing

In this study, an extruded Mg-9Al-1Zn-0.3Mn-0.9Ca-0.6Y (AZXW9110) alloy is subjected to precompression and subsequent annealing (PCA) treatment for improving its bending formability, and the three-point bending properties of the as-extruded material and the precompressed and subsequently annealed (PCAed) material at room temperature are compared. During bending, microcracks formed in undissolved Al 2 Ca, Al 2 Y, and Al 8 Mn 4 Y particles propagate along the grain boundaries or twin boundaries and consequently form a macrocrack in the tension zones of the bending samples of both the materials. However, the bending formability of the PCAed material is 75% higher than that of the as-extruded material owing to the promoted twinning and slip behaviors in the former. The as-extruded material has a strong normal direction (ND) texture and a weak transverse direction (TD) texture, and the ND- and TD-oriented grains are unfavorable for both {10-12} twinning and basal slip in the tension zone of the bending sample of this material, which eventually results in its low bending formability. The PCAed material has a strong extrusion direction (ED) texture, weak TD texture, and spread ND texture. During bending, {10-12} twins are fully formed in the ED-oriented grains, and this {10-12} twinning effectively accommodates the plastic strain in the tension zone. In addition, the activation of basal slip in the ND-oriented grains of the PCAed material is promoted owing to the spread ND texture of this material. Consequently, this material exhibits substantially superior bending formability because of the vigorous {10-12} twinning in its ED-oriented grains and promoted basal slip in its ND-oriented grains. (c) 2021 Chongqing University. Publishing services provided by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ) Peer review under responsibility of Chongqing University

Automated summary

Precompression and subsequent annealing treatment can improve the bending formability of the Mg-9Al-1Zn-0.3Mn-0.9Ca-0.6Y alloy. The PCAed material exhibits higher bending formability due to the promoted twinning and slip behaviors.