In vitro degradation and in vivo osteogenesis of Mg-Zn-Nd-Zr/HA composites prepared by friction stir processing

•The Mg-Zn-Nd-Zr/HA composites exhibit higher osteogenic activity in vivo differently from in vitro osteogenic expression.•The corrosion behavior of Mg-Zn-Nd-Zr/HA composites prepared by friction stir processing depends on comprehensive effects of grain refinement and localized corrosion.•Severe plastic deformation by stirring friction processing in composites preparation leads to significant grain refinement, improved mechanical properties and uniform distribution of reinforcements.•A guiding principle for the design of degradable magnesium matrix composites should be based on comprehensive consideration of the processing method, type, content and distribution of the reinforcement, especially the effect of powder agglomeration on the degradation behavior and biological properties.