Microstructure-Mechanical Properties of Mg-xCa Alloys Produced by Mechanical Alloying-Hot Pressing Process and Their Optimization Using Central Composite Design Method

In the study, Mg-xCa alloys with high mechanical performance were developed using a statistical model central composite design (CCD) method to predict the mechanical properties of Mg and Ca powders produced by powder metallurgy. Powder metallurgy (TM) is a production method that offers great advantages over other production methods. However, there are limited studies in the literature on the production of alloying Ca to eliminate the high degradation rate of pure Mg loss. Mg and Ca powders were subjected to the alloying process for different times as 11.99-14.43-18-21.5-24 h, and after mechanical alloying (MA), grain size measurements of the powders and XRD and SEM-EDS analyses were performed. After MA, the powders were sintered at different temperatures, such as 325-370-437-504-549°C in an argon gas environment under 46 MPa pressure, and samples were obtained. The microstructures, mechanical properties, compressive strength, density values, and XRD-SEM results showed that the secondary phase Mg2Ca increased with increasing Ca content, which indicates the increasing hardness of Mg-xCa alloy. Using the CCD method, the sample's compressive strength, hardness, and density results with optimal values produced from Mg-xCa alloys were determined as 251 MPa, 146 Brinell, and 1.7 g/cm3, respectively. The compatibility of the experimental results with the Regression formula confirms the reliability of the equation.