Liquid Segregation Phenomenological Behaviors of Ti14 Alloy during Semisolid Deformation

Int J Miner Metall Mater

Huo

Song

et al. 2016

The direct-current simulation burning method was used to investigate the burn-resistant behavior of Ti14 titanium alloy. The results show that Ti14 alloy exhibits a better burn resistance than TC4 alloy (Ti-6Al-4V). Cu is observed to preferentially migrate to the surface of Ti14 alloy during the burning reaction, and the burned product contains Cu, Cu 2 O, and TiO 2 . An oxide layer mainly comprising loose TiO 2 is observed beneath the burned product. Meanwhile, Ti 2 Cu precipitates at grain boundaries near the interface of the oxide layer, preventing the contact between O 2 and Ti and forming a rapid diffusion layer near the matrix interface. Consequently, a multiple-layer structure with a Cu-enriched layer (burned product)/Cu-lean layer (oxide layer)/Cu-enriched layer (rapid diffusion layer) configuration is formed in the burn heat-affected zone of Ti14 alloy; this multiple-layer structure is beneficial for preventing O 2 diffusion. Furthermore, although Al can migrate to form Al 2 O 3 on the surface of TC4 alloy, the burn-resistant ability of TC4 is unimproved because the Al 2 O 3 is discontinuous and not present in sufficient quantity.

Section: Burn-resistant Mechanism Of Ti14 Alloymentioning

confidence: 99%

Burn-resistant behavior and mechanism of Ti14 alloy

Int J Miner Metall Mater

Huo

Song

et al. 2016

“…In the initial compression, yield stress is rapidly increased to the limit with the increase of strain. The phenomenon is also provided in the semisolid deformation of the Ti14 alloy (Chen et al 2009(Chen et al , 2012(Chen et al , 2014. However, at the temperature of 1273 K, the stress-strain curves show steady-state characteristic without any obvious peak stress, and the flow stress of the alloy increases markedly and decreases very slowly with the increasing strain in the whole true strain scope of 0-0.75.…”

Section: Flow Behavior At Different Temperaturesmentioning

confidence: 90%

Characterization of semisolid deformation behavior and constitutive analysis of Ti230 alloy

Luo

Wei

et al. 2015

Mech Time-Depend Mater

The semisolid compressive deformation behavior of Ti230 titanium alloy at the temperature range of 1273 K to 1573 K and strain rate range of 0.005 to 5 s −1 has been investigated by hot compressive testing. The relationship between flow stress and deformation parameters and microstructure were discussed. The results show that the alloy expresses obvious yield point in semisolid state. The maximum decreased with decreasing solid phase fraction and/or decreasing strain rate, and a transition in stress occurred at a solid phase fraction close to 0.95, which is considered to be associated with the decrease in amount of solid bridges between grains and the decomposing effects of the liquid on α-Ti matrix. A deformation constitutive equation for Ti230 alloy in semisolid state was established considering high-temperature deformation activation energy Q. Furthermore, microstructural analysis confirmed that increasing temperature could reduce the deformation-resistant stress and lead to the transformation of softening mechanism from plastic deformation of solid particles (PDS) to sliding between the solid particles (SS).

“…The precipitation of acicular Ti 2 Cu along grain boundaries is prone to occur probably because of the segregation of liquid. 20 Under higher strain rates and lower Cu concentrations, less liquid segregate to grain boundaries resulting in less precipitation of acicular Ti 2 Cu along grain boundaries.…”

Section: Correlation Of Microstructure With Cu Concentrationmentioning

confidence: 99%

Effect of Cu concentration on the semi-solid deformation behavior and microstructure of Ti–Cu alloy

Advances in Mechanical Engineering

Luo

Yazhou

et al. 2015

The semi-solid compressive deformation behavior of Ti-Cu alloys was investigated by Gleeble-3500 hot simulator at the deformation temperatures ranging from 1273 to 1473 K with strain rates ranging from 5 3 10 23 to 5 3 10 21 s 21. The relationship between Cu concentration and flow stress was analyzed, and the deformation apparent activation energy was also calculated. The results show that Cu concentration has significant influence on the flows' behavior of Ti-Cu alloys, especially at high semi-solid deformation temperatures. The Ti-14Cu exhibits the highest flow stress at 1273 and 1373 K, Ti-2.5Cu alloy exhibits the highest flow stress at 1473 K, and Ti-7Cu alloy shows the lowest flow stress at all tested temperatures, which corresponds to liquid fraction caused by varied Cu concentration and the deformation temperature. The difference in microstructure suggests that the shape and distribution of Ti 2 Cu precipitates are significantly affected by Cu concentration. The increase in Cu concentration leads to the growth and precipitation of acicular Ti 2 Cu along grain boundaries at high semi-solid deformation temperatures. The deformation apparent activation energy of Ti-14Cu alloy significantly decreases from solid deformation to semi-solid deformation owing to the change in main deformation mechanism from plastic deformation of solid particles to solid particles' slippage and rotation of grain boundaries.