Abstract
Ti-Al alloys have excellent high-temperature performance and are often used in the manufacture of high-pressure compressors and low-pressure turbine blades for military aircraft engines. However, solute segregation is easy to occur in the solidification process of Ti-Al alloys, which will affect their properties. In this study, we used the quantitative phase-field model developed by Karma to study the equiaxed dendrite growth of Ti-4.5% Al alloy. The effects of supersaturation, undercooling and thermal disturbance on the dendrite morphology and solute segregation were studied. The results showed that the increase of supersaturation and undercooling will promote the growth of secondary dendrite arms and aggravate the solute segregation. When the undercooling is large, the solute in the root of the primary dendrite arms is seriously enriched, and when the supersaturation is large, the time for the dendrite tips to reach a steady-state will be shortened. The thermal disturbance mainly affects the morphology and distribution of the secondary dendrite arms but has almost no effect on the steady-state of the primary dendrite tips. This is helpful to understand the cause of solute segregation in Ti-Al alloy theoretically.
Highlights
Dendrite is a common microstructure in the solidification process of pure metals and alloys
Zhao et al [23] studied the effect of thermal coupling strength on the growth of pure Ni dendrite, and the results showed that the thermal coupling strength will affect the front of the dendrite interface, leading to secondary dendrite arms coarsening
The results showed that the increase of the interface width will cause the growth rate of the dendrite tip to decrease, and the thermal disturbance will affect the number and morphology of secondary dendrite arms
Summary
Dendrite is a common microstructure in the solidification process of pure metals and alloys. The results showed that the increase of the interface width will cause the growth rate of the dendrite tip to decrease, and the thermal disturbance will affect the number and morphology of secondary dendrite arms. Li et al [27] simulated the growth process of the equiaxed dendrite of Ti-Al alloy under isothermal and nonisothermal conditions, and the results showed that the initial composition and temperature have a great influence on the dendrite morphology and solute distribution, which will cause the dendrite structure to be underdeveloped, and the lower interface composition. In this work, based on our previous studies [36,37,38,39,40,41,42], the morphology and solute segregation of solidification dendrite growth of Ti-4.5% Al alloy is numerically simulated by using the phase-field model with the thin interface approximation proposed by Karma.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
