TY - JOUR
T1 - Formation mechanism of lamellar alpha in titanium through accurate simulation
AU - Liu, Xueyan
AU - Li, Hongwei
AU - Zhan, Mei
N1 - Publisher Copyright:
© 2019 Elsevier B.V.
PY - 2019/11/30
Y1 - 2019/11/30
N2 - The lamellar α, transformed β matrix and spheroidization products of them combine to form all typical microstructures in titanium alloys. Accurately predicting the formation of lamellar α and revealing the precipitation mechanism therefore become vital for tailoring the microstructure and thus optimizing the properties of titanium alloys. A mixed-mode model combined with cellular automaton is proposed to simulate the process of nucleation and growth of lamellar α phase in isothermal treatment of Ti alloys. In this model, the driving force that is dependent on temperature, the solute concentration in two phases and interface is derived; the soft impingement effect, considering the microscopic morphology evolution of lamellar α phase in two dimensions, is well described by not only approximating the diffusion field function in front of the interface as a polynomial but also introducing the area and interface length of lamellar α into the mass conservation law. A comparision with the interface-controlled and diffusion-controlled models shows that the mixed-mode model gives obviously more accurate description of β-to-α phase transformation kinetics. Furthermore, it is also found that the interfacial migration coefficient, and the microscopic morphology of lamellar α phase to be precipitated have great effects on the mixed mode character (in especial the change in controlled mode) and the kinetics of entire phase transformation process.
AB - The lamellar α, transformed β matrix and spheroidization products of them combine to form all typical microstructures in titanium alloys. Accurately predicting the formation of lamellar α and revealing the precipitation mechanism therefore become vital for tailoring the microstructure and thus optimizing the properties of titanium alloys. A mixed-mode model combined with cellular automaton is proposed to simulate the process of nucleation and growth of lamellar α phase in isothermal treatment of Ti alloys. In this model, the driving force that is dependent on temperature, the solute concentration in two phases and interface is derived; the soft impingement effect, considering the microscopic morphology evolution of lamellar α phase in two dimensions, is well described by not only approximating the diffusion field function in front of the interface as a polynomial but also introducing the area and interface length of lamellar α into the mass conservation law. A comparision with the interface-controlled and diffusion-controlled models shows that the mixed-mode model gives obviously more accurate description of β-to-α phase transformation kinetics. Furthermore, it is also found that the interfacial migration coefficient, and the microscopic morphology of lamellar α phase to be precipitated have great effects on the mixed mode character (in especial the change in controlled mode) and the kinetics of entire phase transformation process.
KW - Cellular automaton
KW - Lamellar alpha precipitation kinetics
KW - Mixed mode character
KW - Mixed-mode model
KW - Morphology evolution
UR - http://www.scopus.com/inward/record.url?scp=85071576485&partnerID=8YFLogxK
U2 - 10.1016/j.jallcom.2019.152085
DO - 10.1016/j.jallcom.2019.152085
M3 - 文章
AN - SCOPUS:85071576485
SN - 0925-8388
VL - 811
JO - Journal of Alloys and Compounds
JF - Journal of Alloys and Compounds
M1 - 152085
ER -