Thermomechanical Processing of AZ31-3Ca Alloy Prepared by Disintegrated Melt Deposition (DMD)

Kamineni Pitcheswara Rao,Yellapregada Venkata Rama Krishna Prasad,Kalidass Suresh,Manoj Gupta

doi:10.3390/cryst10080647

Kamineni Pitcheswara Rao, Yellapregada Venkata Rama Krishna Prasad + Show 2 more

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https://doi.org/10.3390/cryst10080647

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Abstract

Mg-3Zn-1Al (AZ31) alloy is a popular wrought alloy, and its mechanical properties could be further enhanced by the addition of calcium (Ca). The formation of stable secondary phase (Mg,Al)2Ca enhances the creep resistance at the expense of formability and, therefore, necessitates the establishment of safe working window(s) for producing wrought products. In this study, AZ31-3Ca alloy has been prepared by the disintegrated melt deposition (DMD) processing route, and its hot deformation mechanisms have been evaluated, and compared with similarly processed AZ31, AZ31-1Ca and AZ31-2Ca magnesium alloys. DMD processing has refined the grain size to 2–3 μm. A processing map has been developed for the temperature range 300–450 °C and strain rate range 0.0003–10 s−1. Three working domains are established in which dynamic recrystallization (DRX) readily occurs, although the underlying mechanisms of DRX differ from each other. The alloy exhibits flow instability at lower temperatures and higher strain rates, which manifests as adiabatic shear bands. A comparison of the processing maps of these alloys revealed that the hot deformation mechanisms have not changed significantly by the increase of Ca addition.

Highlights

In recent years, magnesium alloys have become popular for use as lightweight structural components in automobile, aerospace and biomedical applications [1,2]
The AZ31–3 wt% calcium (AZ31-3Ca) alloy was prepared by the disintegrated melt deposition (DMD) processing technique developed by Gupta and coworkers [15,16]
The starting microstructure of DMD processed AZ31-3Ca alloy is shown in Figure 1a,b as viewed

Summary

Introduction

Magnesium alloys have become popular for use as lightweight structural components in automobile, aerospace and biomedical applications [1,2]. The alloy faces limitations of creep strength and corrosion resistance. Its creep strength may be enhanced by the addition of alloying additions like rare-earth or alkaline-earth elements. The addition of Ca to magnesium alloys has been studied extensively in view of its cost advantage over the rare-earth elements [4,5,6] and its effect on strength and hot workability has been reviewed recently [6]. Sakai et al [9] reported that addition of 1%Ca enhances the room temperature strength of AZ31 significantly the ductility improves only at temperatures higher than about 150 ◦ C. Ca addition to an extent of 0.7% enhances the corrosion resistance of AZ31 alloy [10] higher additions are not beneficial. The ultimate compressive strength of AZ31 alloy at its service temperature (about 150 ◦ C) increases from 134 MPa to 235 MPa with 2% Ca

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Conclusion