Alloy Design and Properties of New α+β Titanium Alloy with Excellent Cold Workability, Superplasticity and Cytocompatibility

Abstract

Fig. 8. Relationship between the b transus and hardness under as ST condition and after 30 % cold rolling reduction in various alloys.

β-Grain Refinement of α+β-Type Ti–4.5Al–6Nb–2Fe–2Mo Alloy by Using Rare-Earth-Oxide Precipitates

“…22,23) Rare-earth elements (La (0.01 mass%), Y (0.1 mass%), Er (0.1 mass%) or Ce (0.1 mass%)) were added to the base alloy. The ingots were prepared using an argon (Ar)-arc melting furnace with a non-consumable tungsten (W) electrode.…”

Microstructure and Mechanical Properties of an α+β Type Ti-4V-0.6O Alloy

“…4(a), the O content in equiaxed α phase increased with increasing heat treatment temperature. It is well-known that the presence of O in Ti increases the hardness by solid-solution strengthening 7,8) , and the degree of hardening follows a parabolic dependence on the O con- tent 29,30) . This is in good agreement with the experimental results shown in Fig.…”

“…The α phase stabilizability of O is thought to be 10 times larger than that of Al 5) . It is reported that the presence of O in Ti increases the hardness and tensile strength of the material, but decreases the ductility and fracture toughness [6][7][8] .…”

Variations in the Microstructure and Hardness with Solution Treating and Aging Conditions in New .ALPHA.+.BETA. Titanium Alloy Ti-4.5%Al-6%Nb-2%Fe-2%Mo

“…Most aϩb titanium alloys with high b transus such as Ti-6Al-4V or Ti-6Al-7Nb alloy have relatively low hardenability, and solution treating in these alloys forms aЈ martensite. On the other hand, new alloy has very low b transus of 1 156 K, 13) and b phase formed by heat treating in aϩb two-phase region or a single b phase region in alloys with such a low b transus possibly transforms to aЉ martensite and athermal w phase as well as retained b phase. [16][17][18][19] These features of the transformed microstructures in new titanium alloy may also cause different aging response from those of alloys with high b transus.…”

“…Currently, the authors developed new aϩb titanium alloy, Ti-4.5%Al-6%Nb-2%Fe-2%Mo (notation of % indicates mass percent, being eliminated hereafter) possesses much improved cold workability compared with most of commercially used aϩb titanium alloys (noted as new alloy hereafter). 13) While new alloy possesses similar mechanical properties to SP-700 alloy, [14][15][16] biocompatibility was improved by optimization of alloy compositions such as elimination of vanadium, which is contained in SP-700 alloy. Most aϩb titanium alloys with high b transus such as Ti-6Al-4V or Ti-6Al-7Nb alloy have relatively low hardenability, and solution treating in these alloys forms aЈ martensite.…”