Powder metallurgy (PM) of titanium is a potentially cost-effective alternative to conventional wrought titanium. This article examines both traditional and emerging technologies, including the prod...

https://www.tandfonline.com/doi/pdf/10.1080/09506608.2017.1366003

Powder metallurgy of titanium – past, present, and future

The conventional cold-compaction-and-sinter powder metallurgy (PM) approach offers an efficient solution to the near-net shape or preform fabrication of titanium and its alloys for cost reduction and improved chemical homogeneity and refined microstructures. The methods for compacting titanium powder are similar to those used for other ductile powders. The high-purity titanium in the most ductile state is similar to annealed copper in terms of elastic modulus, hardness, elongation, and ultimate tensile strength. The properties of titanium are sensitive to the impurity level, in particular to nitrogen, oxygen, carbon, and iron. Hardness is a convenient measure of the quality of a titanium sponge product. Dilatometric studies of the sintering of titanium-nickel alloys show similar observations and confirm that oxide films on titanium powder surfaces do not need to be reduced by the atmosphere or disrupted by a chemical additive.

Cold compaction and sintering of titanium and its alloys for near-net-shape or preform fabrication

Powder metallurgy with space holder for porous titanium implants: A review

Powder metallurgy (P/M) is a particularly attractive manufacturing process for titanium (Ti) components as conventional shape casting routes are not practical due to the reactivity of molten Ti with most gas atmospheres and with most materials which might serve as crucibles. This chapter discusses the conventional press-and-sinter Ti P/M process. It begins by providing a historical overview of the methods of production for Ti powder and the characteristics of the powders produced. It then reviews key issues in the cold pressing and sintering processes of Ti and its alloys.

Sintering of titanium and its alloys

Few Ti alloys have been designed for ease of sintering. This paper considers the design of alloys for processing using the mixed elemental technique, in which powders are mixed, cold pressed in a die to near net shape and sintered under vacuum at high temperature. The authors describe steps in the process of developing a Ti–Ni–Sn alloy, able to be sintered to near full density at a sintering temperature as low as 1100°C without requiring unusually fine powder or high compaction pressure. Higher sintering temperature allows the Ni content of the alloy to be reduced, but swelling of the alloy probably imposes an upper limit on practical sintering temperature. The increase in green density, and hence sintered density, conferred by Sn in Ti–Sn alloys, and the increase in sintered density due to the high diffusivity of Ni in Ti–Ni alloys, are combined in Ti–Ni–Sn alloys.

Design of titanium alloy for efficient sintering to low porosity

As a result of the better sinterability of reduced powders, the mechanical properties of compacts from these powders are higher than those of compacts from electrolytic powder. As a technique for the production of porous titanium, sintering in thoroughly-dried argon is simpler than vacuum sintering and enables porous parts to be produced with mechanical properties fulfilling the requirements of sintered-filter operation.

Properties of electrolytic and reduced titanium powders and sinterability of porous compacts from such powders

1.

A study was made of the conditions of preparation and physicochemical and physicomechanical properties of sintered titanium-molybdenum alloys containing up to 50 wt% Mo.




2.

An investigation of the corrosion resistance of such alloys in 20% HCl and 40% H2SO4 solutions demonstrated that Ti33Mo powder metallurgy alloys sintered in argon at a temperature of 1200°C exhibit the highest resistance to corrosion attack.




3.

Sintered Ti33Mo alloys may be recommended for the manufacture of porous permeable materials from titanium and molybdenum powders.

D. S. Arensburger

Papers

Properties of electrolytic and reduced titanium powders and sinterability of porous compacts from such powders

Sintered titanium-molybdenum alloys