In-situ neutron diffraction characterization on the phase evolution of γ-TiAl alloy during the wire-arc additive manufacturing process

Chen Shen, Klaus Dieter Liss, Mark Reid, Zengxi Pan*, Yan Ma, Xi Li, Huijun Li

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

γ-phase based titanium aluminide has continuously been attractive because of its potential application in modern light-weight, high-temperature turbines, such as aircraft engines. However, it suffers from its poor plasticity and during manufacturing and processing. In recent years, wire-arc additive manufacturing process has been proved feasible of fabricating γ-phase based titanium aluminide structures with full density and relatively lower cost compared to traditional powder metallurgy processing. In the present research, the temperature process of a single-pass deposition process during the additive manufacturing was simulated as a linear heating (up to 1623 K) and cooling process in a vacuumed furnace, and in-situ investigated using neutron diffraction. As a result, compared to the initial as-fabricated state, the volume fraction of α2-phase increased by 2.54% after the heat treatment. Crystallographic aspects, specifically the α/α2 ↔ γ phase transformation and lattice evolutions of γ-phase are discussed in detail. According to the results obtained, the γ → α2 transition temperature in the present binary alloy is 1393 K, which largely deviates from earlier results collected from γ-phase based titanium aluminides with Nb addition. Also, the lattice evolutions of γ-phase in a function of time/temperature are linear fitted and responses of lattice strains (a, c axis and volumetric) to temperature are calculated.

Original languageEnglish
Pages (from-to)280-287
Number of pages8
JournalJournal of Alloys and Compounds
Volume778
DOIs
StatePublished - 25 Mar 2019

Keywords

  • Additive manufacturing
  • In-situ
  • Neutron diffraction
  • Phase characterization
  • Titanium aluminide
  • Welding

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