Fabrication and characterization of Mg–0.2 at% Ca/α-tricalcium phosphate composites

•Fabrication of magnesium composite with alpha-TCP is conducted.•Due to existence of alpha-TCP particles, microstructure was varied at extrusion.•Properties of composites are dependent on size of alpha-TCP particles. To apply magnesium in biodegradable bone fixation devices, it is favorable to improve its properties through approaches such as by forming composites between magnesium and calcium phosphate. In this study, a powder metallurgical method was used to prepare composites of a magnesium–calcium alloy and α-tricalcium phosphate (α-TCP). Refinement of the α-TCP particle size caused more uniform distribution and microstructure. Consequently, the composite with finer α-TCP particle size had better ductility to the alloy lacking α-TCP. The biodegradation properties were improved by the addition of α-TCP, and the refinement of the α-TCP particles led to a slower degradation rate in electrochemical and immersion tests.