Fabrication and properties of magnesium-calcium alloy via powder metallurgy technique

Abstract

Composition of Mg-Ca alloys were prepared by powder metallurgy (PM) method with addition of different calcium content and sintering temperature. This is to evaluate the effect caused by the amount of calcium content and the influence of sintering temperature in the metal matrix alloy. Calcium act as the alloying element in Mg-Ca is added in by 0.5, 1, 1.5 and 2 weight percentage (wt.%) and sintered at 500, 550 and 600 °C (T1, T2 and T3 respectively) in argon atmosphere. The effect of sintering is also investigated by focusing on the microstructure and properties of sintered sample. XRD analysis shows that the addition of calcium leads to the formation of intermetallic Mg2Ca phase at the border of α-Mg grain boundaries. Particularly, causing an increment in hardness values of the samples. More calcium content leads to smaller grain structure and increase stress between particles. Hence causes embrittlement in the sample alloy. The density of each sample alloy increased from 1.78 g/cm3 to 1.83 g/cm3 while porosity profiles show inverse characteristics upon addition of calcium. Morphological analysis carried out by optical microscope shows increase pores refinement with the increase of sintering temperature together with calcium content in Mg-Ca alloys. Due to the formation of Mg2Ca in the alloy, the trend of corrosion rates show increase profile as calcium content increased. The samples also show an increment as sintering temperature increased. Tafel extrapolation graph shows that the corrosion rate of Mg-Ca alloy increases as calcium content increases. However, there is an only small increment rate difference that is 8.52x10-1 mpy value of most rapid corrosion on Mg-2Ca sintered at 600 °C sample and the slowest rate is 1.59x10-4 mpy on pure Mg sample sintered at 500 °C.