Abstract
The coarse as-cast lamellar microstructure in TiAl alloys is difficult to be broken completely by thermo-mechanical processing.Some remnant lamellar colonies in the deformed microstructure seriously affect the microstructural homogeneity and deteriorate the properties.In this study,it is found that by isother-mal compression at 1230 ℃ and 1250 ℃,the lamellar colonies of Ti-43.5Al-4Nb-1Mo-0.1B(TNM)alloys can be completely broken.This is attributed to the weakened anisotropic deformation behavior of the lamellar colonies due to the isothermal holding treatment before deformation.The deformation behavior at 1230 ℃ was investigated by quasi-in-situ experiments.It is observed that the regions near lamel-lar colony boundaries first undergo dynamic recrystallization at small strain,while the lamellar colonies gradually break down with increasing strain.The adequate fragmentation of lamellar colonies mainly depends on the recrystallization of α lamellae(αL).The isothermal holding at 1230 ℃ leads to an in-crease in the content and thickness of αL,which allows it to assume more deformation and promotes its recrystallization by reaching critical strain.The interrupted γ lamellae(γL)formed by decomposition during isothermal holding facilitates the occurrence of α recrystallization within the lamellar colonies by hindering dislocation movement.In addition,recrystallized γ grains(γR)are gradually dissolved by the formation of α precipitates inside them through the γ → α phase transformation and the subsequent consumption of α precipitates by the recrystallized α grains.
基金项目
National science and Technology Major Project of China(J2019-Ⅵ-0011-0125)
China Postdoctoral Science Foundation(2023MD734201)
ND Basic Research Funds of China(G2022WD)
Shaanxi Province Innovation Capability Support Program(2023-CX-TD-47.T)
NETL
NSTL
万方数据