Kinetics of the ω phase transformation of Ti-7333 titanium alloy during continuous heating

Influence of cooling rate on the precipitation kinetics of nanoscale isothermal ω-phase in metastable β-Ti alloy, Ti–5Al–5Mo–5V–3Cr

“…Also, the nucleation behaviour showed transient nucleation kinetics for both the cases: i.e., an incubation time ( ) is required to reach the critical nucleation size. This early nucleation in the water-quenched sample could be attributed to the higher dislocation density in the sample [49]. In addition, Chen et al [48] reported that an air-cooled sample has shown a higher degree of solute partitioning due to the ageing effect during air cooling.…”

“…10. The transformed fraction represents the ratio between the volume fraction of ωiso precipitates at time t during ageing and the volume fraction formed at the metastable equilibrium state [49,50] and is given by Equation 11 (11) where ρt refers to the electrical resistivity of the alloy at time t during the ageing period, ρ0 refers to the electrical resistivity of the alloy at the beginning of ageing, and ρmeta refers to the electrical resistivity of the alloy at the end of the ageing time.…”

Precipitation hardening and microstructure evolution of the Ti–7Nb–10Mo alloy during aging

“…Hao et al [11] plotted the TTT diagram of Ti-29Nb-13Ta-4.6Zr alloy, and found that the microstructure of the solution-treated alloy at different aging temperatures varies from β + α to α + β + ω, β + ω and β, along with α″ at temperature above 550°C or below 400°C. The metastable ω phase formed during isothermal process (ω iso ) is widely researched [20][21][22][23] and usually brings unexpected embrittlement and obvious rise of Young's modulus [24]. Meanwhile ω phase formed by non-diffusion process (ω ath ), like water quenching, is believed to be smaller than ω iso (~1.5 nm for ω ath and~70 nm for ω iso , both in long axis) with the same composition as the parent β phase [25].…”

Study on Non-Isothermal Transformation of Ti-6Al-4V in Solution Heating Stage

“…Zhou et al [13] studied the ω phase transformation kinetics of Metals 2019, 9, 968 2 of 10 TB-13 titanium alloy during continuous heating by non-isothermal dilatometry. It was found that the exponent n changed continuously with the increase of the transformed volume fraction, while the nucleation and growth mechanism of the ω phase were analyzed based on the local Avrami exponent n. Hui et al [14] investigated the transformation process of the metastable phase β → ω of near β titanium alloy Ti-7333 at different heating rates by non-isothermal dilatometry. The activation energy and phase transformation kinetics models of β → ω were obtained based on the KAS theory and the modified JMA model.…”