Perpustakaan Digital ITB

The effect of silver addition on microstructures and mechanical properties of extruded AZ91 magnesium alloy was studied. The microstructure, texture, mechanical properties and the aging behavior of AZ91 and AZQ910 alloys that were extruded at 400°C with a ram speed of 0.1 mm/s are investigated. The occurrence of dynamic recrystallization, precipitation of -phase Mg17Al12 particles and the formation of basal texture during extrusion are observed by scanning electron microscope equipped with electron backscattered diffraction pattern analysis. Artificial aging treatment (T5) of as-extruded AZ91 and AZQ910 alloys was done at 160°C in an oil bath. The mechanical properties in line with microstructure of extrusion-aged alloys are investigated. Improvement of the precipitation behavior, for both extrusion-aged AZ91 and AZQ910 alloys, contributes a beneficial improvement of tensile properties, compressive properties, and hardness properties. The addition of 0.38 wt. % silver to Mg-9Al-1Zn (wt. %) alloy significantly enhances the age-hardening response. This is associated with large size of lamellar-discontinuous -phase Mg17Al12 precipitates along grain boundary and great amount of continuous -phase precipitates inside the grain. The precipitation strengthening is rather weak due to less amount of silver. However, better compressive properties also can be obtained on the AZ91 alloy with the silver addition.