Non-conventional transformation pathways and ultrafine lamellar structures in γ-TiAl alloys

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

21 Scopus Citations
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Author(s)

  • Dong Wang
  • Jiaming Zhu
  • Hu Xiao
  • Yunzhi Wang

Detail(s)

Original languageEnglish
Pages (from-to)25-34
Journal / PublicationActa Materialia
Volume189
Online published27 Feb 2020
Publication statusPublished - 1 May 2020

Abstract

The mechanical properties of two-phase γ-TiAl alloys depend strongly on the scale of their lamellar microstructures. In this study, we investigate the effect of alloy composition on lamellar thickness in Ti100-xAlx by simulating microstructural evolution during the α2′ → α2 + γ phase transformation using the phase field method. From both existing experimental data and our simulation results we find that the average thickness of γ lamellae first decreases and then increases with increasing Al content. Further analyses reveal that this unique composition-dependence of the lamellar thickness could be associated with non-conventional pseudospinodal decomposition and congruent structural transformation mechanisms that generate ultra-high densities of nuclei at the initial stage, which impacts the later growth processes. The interplay between the number density of nuclei and the number of coalescence events during growth results in the non-monotonic dependence of the lamellar thickness on the alloy composition. These findings may offer new insights on the design of ultrafine lamellar microstructures for γ-TiAl alloys.

Research Area(s)

  • Phase field, Phase transformation, Precipitation, Pseudospinodal decomposition, Titanium alloy