Effect of W Content on the Phase Transformation Behavior in Ti-42Al-5Mn-xW Alloy
Advanced intermetallic β-solidifying γ-TiAl-based alloys have various potential applications in the aerospace and automobile industries due to their low density,functionality at higher temperatures,and high specific strength/modulus.The crucial aspect that needs to be considered when developing a new β-solidifying γ-TiAl alloy is to clarify the influence law of β-stabilizer elements on the phase transfor-mation behavior of γ-TiAl alloys.In this work,the impact of W contents(0.5%-1.0%,atomic fraction)on the phase transformation behavior and microstructure characteristics of Ti-42Al-5Mn-xW(atomic frac-tion)alloy with low cost and superior temperature workability was systematically investigated.The find-ings demonstrate that there were minor changes in the β-phase single region temperature(Tβ)and γphase solvus temperature(Tγ-solv);furthermore,the eutectoid reaction temperature(Teut)increases with the W content from 0.5%to 1.0%.Addition of W influences the solid phase transformation pathway to a cer-tain extent.When the concentration of W increases to 0.5%,the equilibrium phase of the alloy at near service temperature gradually changes from α2 + γ + Laves to βo + α2 + γ + Laves.Additionally,W addition will also have a substantial effect on the lamellar microstructure.The volume fraction of lamellar micro-structure considerably decreased after alloying with(0.5%-1.0%)W for Ti-42Al-5Mn alloy when being treated in the(γ + α + β)triple-phase region followed by furnace cooling.Increasing the W content to 0.8%and 1.0%results in the development of γ and βo grain phases with almost complete removal of α2/γ lamellar structures.However,the W-free and W-bearing Ti-42Al-5Mn alloys show near complete lamellar structures when treated in(α + β)two-phase region followed by furnace cooling.Furthermore,when the content of W increased from 0.5%to 1.0%,an equiaxed grain structure with refined lamellar colonies is typically obtained.
TiAl alloyW contentphase transformationlamellar structuregrain refinement
万方数据
维普
