Abstract
In this study, graphene-oxide (GO)-reinforced Ti–Al–Sn–Zr–Mo–Nb–Si high-temperature titanium-alloy-matrix composites were fabricated by powder metallurgy. The mixed powders with well-dispersed GO sheets were obtained by temperature-controlled solution mixing, in which GO sheets adsorb on the surface of titanium alloy particles. Vacuum deoxygenating was applied to remove the oxygen-containing groups in GO, in order to reduce the introduction of oxygen. The compact composites with refined equiaxed and lamellar α phase structures were prepared by hot isostatic pressing (HIP). The results show that in-situ TiC layers form on the surface of GO and GO promotes the precipitation of hexagonal (TiZr)6Si3 particles. The composites exhibit significant improvement in strength and microhardness. The room-temperature tensile strength, yield strength and microhardness of the composite added with 0.3 wt% GO are 9%, 15% and 27% higher than the matrix titanium alloy without GO, respectively, and the tensile strength and yield strength at 600 °C are 3% and 21% higher than the matrix alloy. The quantitative analysis indicates that the main strengthening mechanisms are load transfer strengthening, grain refinement and (TiZr)6Si3 second phase strengthening, which accounted for 48%, 30% and 16% of the improvement of room-temperature yield strength, respectively.
Highlights
Ti–Al–Sn–Zr–Mo–Nb–Si high-temperature titanium alloys are near-α titanium alloys with excellent high-temperature specific strength and can be used for long-term service at 550–600 ◦ C [1].Typical examples are IMI834 (Ti–5.8Al–4.0Sn–3.5Zr–0.7Nb–0.5Mo–0.35Si–0.06C, UK), Ti–1100(Ti–6Al–2.8Sn–4Zr–0.4Mo–0.45Si, US) and TA29 (Ti–5.8Al–4Sn–4Zr–0.7Nb–1.5Ta–0.4Si–0.06C, China) alloy, which have been extensively used in high-pressure compressor blisks and cases of aero-engine [2,3,4]
Few agglomerations are observed when the addition amount of GO is less than 0.3 wt%
During vacuum deoxygenating at 400 ◦ C, most of oxygen-containing groups in GO were removed, the amount of GO dropped
Summary
Ti–Al–Sn–Zr–Mo–Nb–Si high-temperature titanium alloys are near-α titanium alloys with excellent high-temperature specific strength and can be used for long-term service at 550–600 ◦ C [1]. There is an urgent demand to enhance mechanical properties of high-temperature titanium alloys [5]. Graphene-reinforced metal-matrix composites have shown promising performance in structural applications due to the effective improvement of mechanical properties [14]. 1010 MPa and tensile strength of 1045 MPa. BM can partly relieve the agglomeration and improve the dispersion of graphene by high impact force and shear force to destroy the van der Waals force between graphene platelets [20,21]. GO/high-temperature titanium alloy powders mixed with different addition amounts of GO were prepared by temperature-controlled solution mixing, and vacuum deoxygenating was subsequently used to decompose the oxygen-containing groups in GO and reduce the introduction of oxygen. GO-reinforced Ti–Al–Sn–Zr–Mo–Nb–Si high-temperature titanium-alloy-matrix composites were prepared by HIP. The effects of addition amounts of GO on microstructure characteristics and tensile properties were investigated in detail and the strengthening mechanisms were discussed quantitatively
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