Synthesis of biodegradable Mg-Zn alloy by mechanical alloying: Statistical prediction of elastic modulus and mass loss using fractional factorial design

Biodegradable Mg-Zn alloy was synthesized using mechanical alloying where a statistical model was developed using fractional factorial design to predict elastic modulus and mass loss of the bulk alloy. The effects of mechanical alloying parameters (i.e., milling time, milling speed, ball-to-powder mass ratio and Zn content) and their interactions were investigated involving 4 numerical factors with 2 replicates, thus 16 runs of two-level fractional factorial design. Results of analysis of variance (ANOVA), regression analysis and R2 test indicated good accuracy of the model. The statistical model determined that the elastic modulus of biodegradable Mg-Zn alloy was between 40.18 and 47.88 GPa, which was improved and resembled that of natural bone (30-57 GPa). Corrosion resistance (mass loss of pure Mg, 33.74 mg) was enhanced with addition of 3%-10% Zn (between 9.32 and 15.38 mg). The most significant independent variable was Zn content, and only the interaction of milling time and ball-to-powder mass ratio was significant as P-value was less than 0.05. Interestingly, mechanical properties (represented by elastic modulus) and corrosion resistance (represented by mass loss) of biodegradable Mg-Zn alloy can be statistically predicted according to the developed models.