Effect Of Heat Treatment On Microstructure And Mechanical Properties Of Az61 Magnesium Alloys

2012 
Magnesium alloys have been increasingly considered as an attractive material in the transportation industry. Extruded magnesium alloys have been found in the center of interest combining their lightweight, surface quality with the wide range of possible achievable geometries. In this study, the AZ61 alloy has been chosen for investigation as one of the most common commercial magnesium wrought alloys. The microstructure change and Mgl7AI2 precipitate in the alloy had been investigated and its influence on hardness had been studied. After primary microstructure characterization and mechanical testing in the as-extruded condition the specimens have been subjected to heat treatment to the temperature 400°C for one hour followed by quenching in the water. Specimens treated were found to have a coarse grain, homogeneous structure with a substantial increase in grain size. Then the specimens are aged at temperature 200°C for half and two hours followed by quench in the water. Optical observations reveal Mg17AI2 precipitations grow in the form of needle shape within the grain after two hour aging. The hardness and mechanical properties of the AZ61 magnesium alloy is also found to increase owing to secondary hardening by precipitation strengthening.
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