ISSN 0412-1961
CN 21-1139/TG
Started in 1956

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 , Volume 56 Issue 7 Previous Issue
 Select Microstructure and Tensile Properties of Ti-43.5Al-4Nb-1Mo-0.1B Alloy Processed by Hot Canned Extrusion LIU Xianfeng, LIU Dong, LIU Renci, CUI Yuyou, YANG Rui Acta Metall Sin, 2020, 56 (7): 979-987.  DOI: 10.11900/0412.1961.2019.00388 Abstract   HTML   PDF (5319KB) ( 84 ) β solidifying γ-TiAl alloys are being considered for high-temperature application in the aerospace and automotive industries as high efficiency materials which can withstand temperatures up to 800 ℃ and owns attractively thermal and mechanical properties. Through thermos-mechanical process can obtain excellent alloy properties, such as high strength and better elongation. But it will cause anisotropy. Ti-43.5Al-4Nb-1Mo-0.1B alloy rectangular bar was prepared by isothermal hot canned extrusion process. The OM, SEM, XRD, TEM and tensile methods were used to study the microstructure and tensile properties of the rectangular rods in different states and locations. The results show that the extruded structure of the rectangular rods is relatively uniform and there is no significant difference in the microstructure at different locations. The extrusion deformation makes the orientation of the lamellar uniform, tending to be parallel to the extrusion direction; γ phase in the grain boundary exists in the three forms of graininess, bulk and strip; the β phase is shredded during extrusion and is elongated in a parallel extrusion direction. Under the TEM observation, lamellar at the edge of the bar was completely shredded, and lamellar at the core position was elongated after lamellar was broken. A large number of ω0 phases are generated in the β0 phase, and the phase relationship of the two follows: [$111ˉ$]$β0$//[0001]$ω0$, {110}$β0$//{$21ˉ1ˉ0$}$ω0$. The tensile strength reaches 1000 MPa or more and elongations are about 0.5% of the rectangular bar at room temperature; the yield strength is above 400 MPa at 800 ℃, which exhibits remarkable plasticity. After the ageing treatment of the hot extruded alloy, a large amount of lens-shape γ phase is formed in the β0 phase, and the ageing treatment improves the high temperature tensile properties of the alloy, but the ω0 phase can not be eliminated.