Computer simulation and experimental investigation of the spinodal decomposition in the β Ti-Cr binary alloy system

Abstract

The spinodal decomposition of the ␤ Ti-Cr binary alloys system is still questionable, because there are only rare experimental and thermodynamics data; moreover, simulation results for a real alloy system have not been found. Transmission electron microscopy (TEM) and quantitative computer simulations based on Khachaturyan's diffusion equation have been employed to study the microstructural evolution occurring in the metastable ␤ Ti-Cr alloys. Our study results reveal that the metastable ␤ Ti-Cr undergoes a phase separation reaction ␤ → titanium rich (␤ 1 ) ϩ chromium rich (␤ 2 ) through a spinodal decomposition. The coherent two-phase fields show extremely fine platelike precipitates distributed homogenously through the bcc matrix, which are parallel to the {100} plane. Those precipitates are highly elastic induced from the first step of the phase separation. There is good agreement between the observed microstructure and the simulation results. The mode of formation of ␣ phase is also discussed.

Phase evolution in laser-deposited titanium-chromium alloys

“…The oxygen content in the glove box has been reported in the ␤ phase of these alloys for Tirich compositions. [8,12,13] The metastable ␤ phase tends to was maintained below 10 ppm during all the depositions. The measured powder flow rate was 2.57 g/min, while the decompose into the solute-lean ␤ 1 and solute-rich ␤ 2 phases.…”

“…There have been a number of studies on the phase 760 W Nd:YAG laser, which produced near-infrared laser radiation at a wavelength of 1.064 m, was used for all the transformations occurring in Ti-Cr alloys as a function of composition and heat treatments. [8][9][10][11][12][13] A miscibility gap depositions. The energy density was in the range of 30,000 to 100,000 W/cm 2 .…”

“…While earlier studies report decomposition were sectioned using electrodischarge machining (EDM) and subsequently investigated by SEM in a PHILIPS* XL30 by a nucleation and growth mechanism, [12,13] more recent studies contend that the matrix undergoes a spinodal *PHILIPS is a trademark of Philips Electronic Instruments Corp., Mahdecomposition. [8,9] Menon and Aaronson [10] and Mebed wah, NJ. and Miyazaki [8] have superimposed the calculated metastable phase diagram for Ti-Cr alloys consisting of the chemifield-emission gun-scanning electron microscope and by cal and coherent spinodal lines on the equilibrium-phase TEM in a PHILIPS CM200 transmission electron microdiagram.…”

Characterising the microstructure and properties of thermally aged aerospace β-21s titanium alloy, Ti - 15Mo - 3Nb - 3Al - 0.2Si

“…al paper on the effect of ternary additions on decomposition of β phase in Ti-V and Ti-Mo alloys, by Miyazaki et. al on ageing effects of phase separating Ti-Cr alloys, among several others [8,13,14]. These authors concluded that α precipitated homogenously on the lean β regions and results in a finely dispersed, uniform distribution of α in the β matrix.…”

“…al paper [14]on the effect of ternary additions on decomposition of β phase in Ti-V and Ti-Mo alloys, by Miyazaki et. al [13] on ageing effects of phase separating Ti-Cr alloys, among several others. Conclusions from this show that α is likely to precipitate on leaner β regions (typically 0.05µm in size).…”