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摘要
Microstructure and mechanical properties of laser deposited complex quaternary Ti-34Nb-7Zr-7Ta (all wt%), an orthopedic load-bearing implant alloy, has been investigated in detail in both as-deposited as well as heat-treated (beta-solutionized and quenched) conditions. The difference in stress-strain behavior of this alloy in the above conditions has been characterized using scanning electron microscopy (SEM), orientation imaging microscopy (OIM (TM)) and transmission electron microscopy (TEM). Compared to the sample in heat-treated condition, the as-deposited sample showed evidence of strong growth related texture. Again in the as-deposited post tensile-tested condition formation of a high density of shear bands, possibly arising from slip localization due to shearing of omega precipitates in the 13 matrix is observed. TEM investigations also show the presence of lenticular shaped deformation induced or phase within the shear bands. In contrast, in case of the beta-solutionized sample, twinning and the formation of stress-induced plates appears to be the primary mode of deformation. The change in deformation mechanism and thus the tensile property of this alloy could be attributed to the crystallographic texture along the growth direction as well as diffusion mediated isothermal omega precipitates, that cause an enrichment of Nb and Ta in the beta matrix, during the laser-deposition process. This is no longer present after the solutionizing treatment.
- 出版日期2012-12
