Mechanical properties of age-hardened titanium-aluminum alloys

Deformation Behavior of an Age-Hardenable Beta+Alpha-Two Titanium Alloy

“…As is well known, changing the dislocation glide mechanism from shear to by-pass of the precipitate particles can cause a dramatic change in slip distribution at low temperatures. This was demonstrated in Ti-Al alloys [ 14], in which homogeneously distributed fine slip occurs when large Ti 3 A1 precipitates (= 70 nm diam.) are looped but inhomogeneous, coarse slip results when smaller particles, 25-50 nm diameter, are sheared.…”

Effect of Aging on Fatigue-Crack Growth Behavior of a High-Temperature Titanium Alloy

“…This phenomenon can be largely attributed to the formation of the 2 phase, which may lead to the increase of the critical resolved shear stress (CRSS). 3,11) When the coherent 2 particles are cut by the moving dislocations in the aged condition, their strengthening effect is reduced. The active slip plane is weakened and subsequent slip will occur on this slip plane preferentially, 9,11) which makes the width of the individual slip band decreased and the spacing between the adjacent slip bands increased, viz.…”

“…For near-titanium alloys, depending on alloy composition, aging may result in the precipitation of incoherent silicide and coherent 2 phase based on Ti 3 Al, as well as the breaking-up of interplatelet films. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] These microstructrual changes will, in turn, lead to a decrease in ductility and a certain extent of gain in strength. [2][3][4][5] The aging treatment may also affect the creep and low cycle fatigue (LCF) properties in a complicated way.…”

The Alloying of Titanium Aluminides with Carbon

“…The precipitation of Ti3Al produces a relatively small increase in the yield stress, but has profound effects on the fracture properties. Generally, Ti3Al precipitation decreases the fracture toughness [54,93], although the degree of embrittlement is sensitive to the actual size distribution of the Ti3Al particles [94]. It also decreases resistance to stress corrosion cracking in saltwater [95].…”

“…In 1970, Lutjering and Weissmann [94] investigated the mechanical properties of age-hardened titanium alloys (14.5 to 18.1 at% Al) and claimed that a desired critical particle size of Ti3Al dispersions and interparticle distance can be obtained by proper heat treatment, so that a dislocation by-pass mechanism will be operative rather than a cutting mechanism. They reported that the moving dislocations were able to shear the particles upon plastic deformation when the interparticle distances were less than about 80 nm (particle size, ~20 nm in diameter and ~70 nm in length).…”