Scandium (Sc) Behavior in High Temperature Ti Alloys

De Hai Ping; S.Q. Wu; Y. Yamabe-Mitarai

doi:10.4028/www.scientific.net/KEM.520.57

Paper Titles

Design of Low Cost High Performance Powder Metallurgy Titanium Alloys: Some Basic Considerations
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High Performance Titanium Alloy Compacts by Advanced Powder Processing Techniques
p.30

Rare Earth Element: Is it a Necessity for PM Ti Alloys?
p.41

Microstructure Development and Alloying Elements Diffusion during Sintering of Near-β Titanium Alloys
p.49

Scandium (Sc) Behavior in High Temperature Ti Alloys
p.57

Modification of Sintered Titanium Alloys by Hot Isostatic Pressing
p.63

Preparation, Microstructure and Properties of Ti-6Al-4V Rods by Powder Compact Extrusion of Powder Mixture
p.70

Porous Ti-6Al-4V Alloy Prepared by a Press-and-Sinter Process
p.76

Comparison of Blended Elemental (BE) and Mechanical Alloyed (MA) Powder Compact Forging into Ti-6Al-4V Rocker Arms
p.82

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Scandium (Sc) Behavior in High Temperature Ti Alloys

Abstract:

The microstructural evolution and elevated temperature tensile properties of Ti-6.6Al-5.2Sn-1.8Zr-(0~3.8)Sc (wt%) alloys have been investigated. The Sc-added alloys showed improved yield strength at 650°C and 750°C and with the elongation above 10%. Minor addition of Sc was found to significantly reduce the as-cast grain size. Higher amount of Sc additions resulted in the formation of high density of Sc-oxide, which causes the high strength at elevated temperatures and the reduction of ductility. High density of α2-Ti3Al fine precipitates with an average size of about 20 nm were observed inside equiaxed primary α (αp) grains in the Sc-free or minor Sc added alloys. However, precipitation free zone (PFZ) also formed in those alloys, where grain boundaries are free from any precipitates. Higher Sc addition was found to hinder the formation of PFZ and α2–precipitates.