Study On The Effect Of B And Y On The Microstructure And Properties Of High Temperature Titanium Alloys

Most of the short time high temperature titanium alloys used above600℃are near titanium, it has significant application value in aerospace,especially forthe Engine Parts. In this paper, the effects of alloy composition and smelting wayfor the microstructure were studied. Effect of B and Y element on the ISM meltingtitanium alloy microstructure and mechanical properties were investigated. The βtransition temperature was measured, the change of the phase composition andtensile properties were compared after different solution treatment temperature.after adding Y, cyclic oxidation at650℃was analyzed on the alloy. the influenceof alloy composition and mold preheat temperature was analyzed through Spiralflow sample on the flow properties of the titanium alloys.After scanning electron microscopy(SEM) analysis of the button ingot by arcmelting, the more content of B, the more precipitated black TiB whisker and grainsize became finer, but there exists a critical value, which is0.3%. Y is similarwith B, the difference is the precipitates are white spherical Y2O3. Through theline scan of the interface, it found that B and Y can reduce the thickness ofinterfacial reaction layer, from the interface to the substrate, the content of eachelement has changed and the hardness showed a gradual downward trend.the results showed that the microstructure of the alloy is the typicalwidmanstatten, the compressive strength and strain is1757MPa and23.0%,respectively without B and Y. It increased to1858MPa and26.5%after adding Y,The shaping property has decreased after adding B and Y. Y can improve theoverall performance of the alloy, while shaping property of B and Y became bad inorder to improve the strength. It found that983℃was β transformationtemperature through differential thermal analysis. After solution treatment at960℃and1020℃, the content of-phase has decreased and tissue reduced in size, therewas no significant change in the composition, as the raise of the solutiontemperature, the tensile strength improved.The results of the Cyclic oxidation showed that after adding Y, the oxidationweight gain decreased, as well as the oxide particle size. The oxide layer becamenanoscale after B,Y added together. It found that By the oxide particles was TiO2through spectroscopy (EDS) and X-ray diffraction (XRD) analysis, the phasecomposed of the alloy is-Ti and TiO2. The content of Ti and Al in the oxide layerexhibits a complementary trends, Y promoted the densification of the Al2O3protective layer to improve the oxidation resistance of the alloy. Mobility experiments showed that the diversity of alloying elements leads to increasedviscosity of the alloy composition, high mold preheat temperatures helped improveliquidity.