Research Project

Thermo-Mechanical Processing of Mg Alloys

This DoD project investigates and characterizes the microstructural evolution of magnesium and magnesium alloys under high temperatures and severe plastic deformation. Electron backscatter detection, X-ray diffraction, and conventional microscopy are being used together with serial sectioning to study the microstructure of magnesium following thermo-mechanical processing.

Equal Channel Angular Extrusion (ECAE)

Equal Channel Angular Extrusion (ECAE)

Interest is being shown in Mg due to its light weight and high potential strength. However, traditional mechanical processing is difficult due to Mg’s anisotropic material properties. A severe plastic deformation (SPD) method called Equal Channel Angular Extrusion (ECAE) has had good results with Mg above approximately 0.5 homologous temperature. This project investigates the effects temperature, strain-rate, and processing route on the microstructural evolution of Mg and an aluminum containing Mg alloy called AZ31 following ECAE processing. Electron backscatter detection, X-ray diffraction, and microscopy are used to characterize the microstructures. In addition, a serial sectioning system using femtosecond laser ablation is being developed which will be used to construct a 3-D model of Mg.

Of particular interest in the thermo-mechanical processing of Mg is a recovery-like process called dynamic recrystallization (DRX). During DRX, new grains nucleate and grow, generally resulting in grains with fewer dislocations than the parent grains and a change in texture. DRX occurs readily in Mg at many of the temperatures and strain-rates used in ECAE and is a significant factor in the resultant mechanical properties, but the process and mechanisms involved are poorly understood. To remedy this, in-situ diffraction experiments will be performed during ECAE to provide insight into orientation evolution and grain growth during DRX.

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