Ti-based alloys are widely used in biomaterials owing to their excellent biocompatibility. In this study, Ti- Mn-Cu alloys are prepared by high-energy ball milling, magnetic pulsed compaction, and pressureless sintering. The microstructure and microhardness of the Ti-Mn-Cu alloys with variation of the Cu addition and compaction pressure are analyzed. The correlation between the composition, compaction pressure, and density is investigated by measuring the green density and sintered density for samples with different compositions, subjected to various compaction pressures. For all compositions, it is confirmed that the green density increases proportionally as the compaction pressure increases, but the sintered density decreases owing to gas formation from the pyrolysis of TiH2 powders and reduction of oxides on the surface of the starting powders during the sintering process. In addition, an increase in the amount of Cu addition changes the volume fractions of the α-Ti and β-Ti phases, and the microstructure of the alloys with different compositions also changes. It is demonstrated that these changes in the phase volume fraction and microstructure are closely related to the mechanical properties of the Ti-Mn-Cu alloys.
The effects of processing parameters on the flow behavior and microstructures were investigated in hot compression of powder metallurgy (P/M) Ti-6Al-4V alloy. The alloy was fabricated by a blended elemental (B/E) approach and it exhibited lamellar α+β microstructure. The hot compression tests were performed in the range of temperature 800-1000°C with 50°C intervals, strain rate 10−4-10 s−1, and strain up to 0.5. At 800-950°C, continuous flow softening after a peak stress was observed with strain rates lower than 0.1 s−1. At strain rates higher than 1 s−1, rapid drop in flow stress with strain hardening or broad oscillations was recorded. The processing map of P/M Ti-6Al-4V was designed based on the compression test and revealed the peak efficiency at 850°C and 0.001 s−1. As the processing temperature increased, the volume fraction of β phase was increased. In addition, below 950°C, the globularization of phase at the slower strain rate and kinking microstructures were found. Based on these data, the preferred working condition of the alloy may be in the range of 850-950°C and strain rate of 0.001-0.01 s−1.
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Medical technologies are gaining in importance because of scientific and technical progress in medicine and the increasing average lifetime of people. This has opened up a huge market for medical devices, where complex-shaped metallic parts made from biocompatible materials are in great demand. Today many of these components are already being manufactured by powder metallurgy technologies. This includes mass production of standard products and also customized components. In this paper some aspects related to metal injection molding of Ti and its alloys as well as modifications of microstructure and surface finish were discussed. The process chain of additive manufacturing (AM) was described and the current state of the art of AM processes like Selective Laser Melting and electron beam melting for medical applications was presented.
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