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Item Influence of boron addition to Ti-13Zr-13Nb alloy on MG63 osteoblast cell viability and protein adsorption(2015) Majumdar P.; Singh S.B.; Dhara S.; Chakraborty M.Cell proliferation, cell morphology and protein adsorption on near ?-type Ti-13Zr-13Nb (TZN) alloy and Ti- 13Zr-13Nb-0.5B (TZNB) composite have been investigated and compared to evaluate the effect of boron addition which has been added to the Ti alloy to improve their poor tribological properties by forming in situ TiB precipitates. MG63 cell proliferation on substrateswith different chemistry but the same topography was compared. TheMTT assay test showed that the cell viability on the TZN alloy was higher than the boron containing TZNB composite after 36 h of incubation and the difference was pronounced after 7 days. However, both the materials showed substantially higher cell attachment than the control (polystyrene). For the same period of incubation in fetal bovine serum(FBS), the amount of protein adsorbed on the surface of boron free TZN sampleswas higher than that in the case of boron containing TZNB composite. The presence of boron in the TZN alloy influenced protein adsorption and cell response and they are lower in TZNB than in TZNas a result of the associated difference in chemical characteristics. � 2014 Elsevier B.V. All rights reserved.Item Influence of in situ TiB reinforcements and role of heat treatment on mechanical properties and biocompatibility of ? Ti-alloys(2012) Majumdar P.; Singh S.B.; Dhara S.; Chakraborty M.The effect of heat treatment on the mechanical properties of Ti-35Nb-5.7Ta-7.2Zr (TNZT) and Ti-35Nb-5.7Ta-7.2Zr-0.5B (TNZTB) alloys has been investigated. In the case of TNZT alloy, the presence of ? phase in the matrix has a greater effect on strength and hardness than the presence of secondary ? precipitates. The TNZTB alloy shows higher hardness and tensile strength than the TNZT alloy due to the formation of hard TiB precipitates in the matrix of the former. However, the boron free alloy offers higher ductility than the boron containing alloy. Presence of TiB precipitates in the matrix increases the strength of the TNZTB alloy when ? precipitates are present in the matrix. However, the boride precipitates have no substantial influence on the strength of the TNZTB alloy when ? phase in the matrix is replaced by the ? phase. The elastic modulus of the TNZT samples shows a very small variation with different heat treatment conditions. The TNZT alloy samples containing ? and ? phases show higher elastic modulus than the samples containing ? and ? phases. The elastic modulus of the TNZTB alloy is higher than that of the TNZT alloy due to the formation of high modulus TiB particles in the matrix. Both the alloys show better cell adhesion and spreading than the control material (polystyrene). However, the boron free Ti-alloy shows better cell attachment than the boron containing Ti-alloy. � 2012 Elsevier Ltd.Item Effects of heat treatment on evolution of microstructure of boron free and boron containing biomedical Ti-13Zr-13Nb alloys(2012) Majumdar P.In the present study, the effects of heat treatment on the microstructure of Ti-13Zr-13Nb (TZN) and Ti-13Zr-13Nb-0.5B (TZNB) alloys have been investigated. Depending on the heat treatment conditions, the microstructure of the heat treated TZN alloy consisted mainly of elongated and/or equiaxed ?, ? or martensite. Slow cooling (furnace or air cooling) from the solution treatment temperature produced ? and ? phases in the microstructure. Rapid cooling (water quenching) resulted in martensite and retained ? when the solution treatment temperature was above or close to ? transus. However, martensite was not formed after water quenching from a solution treatment temperature which was below ? transus due to partitioning effect of the alloying elements. Increasing the cooling rate from the furnace cooling to the air cooling led to finer microstructure. Aging of water quenched samples transformed the martensite, if present, into ? and ?, and the morphology of ? phase changed from elongated to equiaxed and enhanced the growth of ?. The microstructure of all the TZNB samples consisted of dispersed precipitated particles of TiB in the matrix. The majority of the boride particles showed an acicular (needle like) morphology. The other phases present in the TZNB alloy were similar to those in the similarly heat treated TZN alloy. Moreover, a growth of ? phase was observed in the microstructure of TZNB alloy when compared with that of TZN alloy. � 2012 Elsevier Ltd.Item The role of heat treatment on microstructure and mechanical properties of Ti-13Zr-13Nb alloy for biomedical load bearing applications(2011) Majumdar P.; Singh S.B.; Chakraborty M.The suitability of heat treated Ti-13Zr-13Nb (TZN) alloy for biomedical load bearing applications has been investigated. Depending upon the heat treatment conditions, the microstructure of TZN alloy mainly consists of ?, ? or ?" martensite phases. In general, for all the deformation and solution treatment temperatures the variation of the hardness and tensile strength with cooling rate is similar. The elastic modulus of TZN alloy decreases with an increase in cooling rate from the solution treatment temperature. Relatively fine ?+? microstructure increases the hardness and tensile strength. The presence of martensite and/or retained ? in the microstructure decreases the hardness and elastic modulus and increases the ductility substantially whereas higher amount of ? phase in the matrix increases the elastic modulus. Decomposition of martensite and retained ? into ? phase during aging increases the hardness, elastic modulus and tensile strength and decreases the ductility. Among the samples studied, the aged TZN sample, which was deformed and solution treated at 800 �C followed by water quenching, is a promising candidate for the application as implant material. � 2011 Elsevier Ltd.