Effects Of Zirconium Element Content On Microstructures And Properties Of Cast Ti-1100 Alloys

High temperature titanium alloy has been widely used in aerospace due to its excellent comprehensive properties.The 600?is highest using temperature of high temperature titanium alloy,principally concentrated on wrought process.At present,the high temperature titanium alloy structural parts used in aerospace field are developing rapidly in the direction of large,complex and thin wall,which provides an opportunity for the development and application of cast high temperature titanium alloy.Therefore,it is imperative to research cast high temperature titanium alloy applied to 600?.In this paper,the influence of Zr contents(2wt.%,4wt.%,6wt.%,8wt.%and 10wt.%)on the microstructure,high-temperature oxidation resistance,friction and wear properties of Ti-1100 alloys in casting and heat treatment were investigated.The following results were obtained.(1)The microstructures of Ti-1100-x Zr alloys in casting and heat treatment are all belong to widmanstatten structure.The microstructures of the alloys are refined with the increase of the Zr content.The prior?grain size and?-laths spacing of casting alloy changed from 515?m of 2wt.%Zr to 197?m of 10wt.%Zr and from 6.8?m of 2wt.%Zr to2.5?m of 10wt.%Zr,which decreased 161.4%and 172%,respectively.After heat treatments,the prior?grain size and?-laths spacing were larger than the as-cast alloys,also,after1050?×1h heat treatment,the increase of Zr element promotes the precipitation of silicide in alloy.(2)The?/?transus temperature shows a trend of decrease with the increase of the Zr content.The?/?transus temperature of casting alloy changed from 1038?of 2wt.%Zr to998?of 10wt.%Zr.(3)According to the 600?and 120h high temperature oxidation experiment,we can found that the kinetic curves of oxidation of Ti-1100-x Zr alloys in casting and heat treatment follow the rule of straight line-parabola,and with the increase of Zr content,the Ti-1100-x Zr alloys possessed low oxidation resistance.The oxidation surfaces of Ti-1100-x Zr alloys were mainly composed of?-Ti and Ti O₂.The same composition of alloys,the oxidation resistance of 1050?×1h is better than 1000?×1h,the casting alloys possess poor oxidation resistance.(4)The wear rate of Ti-1100-x Zr alloys in casting and heat treatment decreased with the increase of temperature.The wear rate of as-cast Ti-1100-x Zr alloys at 600?compared with room temperature was reduced by 77.9%-91.3%,compared with 500?was decreased by 38.1%-72%.Meanwile,with the increase of Zr content,the wear rate of Ti-1100 alloys in casting and heat treatment at room temperature showed a tread of increase,while that in high temperature is opposite.(5)The friction coefficient of Ti-1100-x Zr alloys in casting and heat treatment increased with the increase of temperature.The friction coefficient and its range-ability of Ti-1100-x Zr in casting and heat treatment at high temperature is larger than that of room temperature.The room temperature wear mechanism of Ti-1100-x Zr alloys in casting and heat treatment is mainly adhesive wear and abrasive wear.The elevated temperature wear mechanism of Ti-1100-x Zr alloys is mainly mild oxidation wear,accompany with slight abrasive wear and fatigue wear.