Microstructure, mechanical, corrosion properties and cytotoxicity of beta‑calcium polyphosphate reinforced ZK61 magnesium alloy composite by spark plasma sintering.

Magnesium alloy (ZK61) and beta-tricalcium phosphate (β-TCP) composite ZK61/xβ-TCP (x = 0, 5, 10, 15 wt%) are fabricated using spark plasma sintering (SPS). In this study, the microstructure, mechanical properties, degradation behavior in simulated body fluid and cytotoxicity tests of composite were investigated. The results show that when the content of β-TCP was 5 wt%, which could be evenly distributed on the boundary of ZK61 particles. But agglomeration phenomenon appeared when the content of β-TCP reached 15 wt%. The hardness and the compressive strength increase with increasing of β-TCP content, and ZK61/15β-TCP achieves a maximum Vickers hardness of 94.81 HV0.1 and compressive strength of 402 ± 9 MPa. The immersion tests indicate that corrosion resistance of the composites are better than that of ZK61 matrix, especially ZK61/5β-TCP. Corrosion products of the composite surface are mainly Mg(OH)2, HA and Ca3(PO4)2. The cytotoxicity tests indicate that composite extracts have no toxicity to L-929 cells. These results suggest that ZK61/xβ-TCP composites are promising candidate for degradable implant materials.