Microstructure Evolution of AZ80 Magnesium Alloy during Multi-Directional Forging Process

Abstract

Grain refinement of a magnesium alloy, AZ80, was studied in multi-directional forging (MDF) with decreasing temperatures from 683 to 573 K. The MDF was carried out up to accumulative true strains of around 7 with changing the loading direction from pass to pass. The structural changes are characterized by the alternate appearance of fine dynamic recrystallized (DRXed) grains (with many dynamic granular Mg 17 Al 12 phases) and coarse DRXed grains (without Mg 17 Al 12 phases) in the sample, the expansion of the fine grains area, and the refinement of (DRXed) grains in the fine grains area during the MDF process. The non-uniform dynamic precipitation of the Mg 17 Al 12 phase may attribute to the inhomogenous Al content distribution in the Mg matrix. These Mg 17 Al 12 phase retards the growth of the DRX grains, which in turn results in the formation and the expansion of the fine grains area during the MDF process with decreasing temperature.

Microstructures and mechanical properties of AZ91 magnesium alloy processed by multidirectional forging under decreasing temperature conditions

“…To the best of our knowledge, most investigations of MDF have 3 concentrated on using this procedure to process aluminum alloys [18] and ferroalloys [19]. However, only a few studies have been reported on MDF of magnesium alloys [20][21][22][23]. Our previous work has investigated the microstructure and mechanical properties of micron-SiCp/AZ91 magnesium matrix composite processed by MDF [24,25].…”

Research on AZ80 + 0.4%Ce (wt %) Ultra-Thin-Walled Tubes of Magnesium Alloys: The Forming Process, Microstructure Evolution and Mechanical Properties

“…With the accumulation of strain, the orientation of the grains turns in the direction that is most favorable to the slip and the twins disappear (shown in Figure 6c,d). Furthermore, the distortion energy stored by twinning and the activation of non-basal slip are responsible for the nucleation of dynamic recrystallization (DRX) [27]. In addition, Figure 6a,b reveal that the "necklace" structure is full of matrix, indicating that DRX occurs and the grain begins to refine [28].…”

Microstructures and mechanical properties of SiCp/AZ91 magnesium matrix nanocomposites processed by multidirectional forging

“…equal channel angular pressing (ECAP), high-pressure torsion (HPT), multidirectional forging (MDF) and accumulative roll-bonding (ARB) etc., are now available, MDF seems to be especially attractive for its potential for scaling up of relatively large samples that can be suitable for industrial applications [18,19]. So far, most investigations of MDF have concentrated on using this procedure to process pure metals or metallic alloys [20][21][22][23][24][25][26]. Our previous work has investigated the microstructure and mechanical properties of micron-SiCp/AZ91 magnesium matrix composite processed by MDF [27,28].…”