Aging treatment and mechanical properties of Ti-29Nb-13Ta-4.6Zr alloy for biomaterial applications coated with bioactive calcium phosphate invert glass

In recent years, the opportunity of the hard tissues such as bones, hip joints and tooth to be replaced by metallic biomaterials is increasing. In general, metallic biomaterials lack bioactivity, which is the ability to directly form a chemical bond with bones. Therefore, the bioactive surface modifications on surface of metallic biomaterials have been investigated and applied. Among them, the calcium phosphate invert glass coating method, which is dip-coating treatment (DCT), can be granted the bioactivity on the surface of all-type titanium alloy, Ti-29Nb-I3Ta-4.6Zr (TNTZ) alloy, for biornaterial applications. In this study, aging characteristics and mechanical properties of TNTZ alloy surface-modified with DCT were investigated. There is an oxide layer and a case near boundary between calcium phosphate invert glass layer and TNTZ surface in TNTZ surface-modified with DCT (TNTZ(DCT)). A very fine omega phase precipitates in an equiaxed beta phase with an average diameter of 20 pm at a distance of 200 pm from specimen surface. On the other hand, the microstructure of aged TNTZ(DCT) has an alpha phase. The tensile strength of TNTZ(DCT) is around 30% greater than that of as-solutionized TNTZ (TNTZ(ST)) - On the other hand, the elongation is around 48% smaller than that of TNTZ(ST). Tensile strength of aged TNTZ(DCT) is around 26% greater than that of TNTZ(DCT). While the elongation of aged TNTZ(DCT) is around 52% smaller than that of TNTZ(DCT). Fatigue limit of TNTZ(DCT) is nearly equal to that of TNTZ(ST). Fatigue limit of aged TNTZ(DCT) is around 80 MPa greater than that of TNTZ(ST). Fatigue limits of TNTZ(DCT) and aged TNTZ(DCT), where their fatigue specimen surfaces are mirror-polished, rise as compared with those of TNTZ(DCT) and aged TNTZ(DCT), where their fagigue specimen surfaces are shot-blasted.