Effect Of Zr On The Microstructure And Properties Of Short-term High Temperature Titanium Alloys

S Short-term high-temperature titanium alloy in the field of aerospace has a great role,especially in the core engine parts is even more indispensable.Short-term high-temperature titanium alloy,especially the use of temperature above 600?for short-term high-temperature titanium alloy is the vast majority of nearly ? alloy,the most important of which is Ti-Al-Sn-Zr-Mo-Si alloy.As the important alloying element in Ti-Al-Sn-Zr-Mo-Si system,Zr is the most widely used neutral element in high temperature titanium alloy.Zr can form infinite solid solution in ?-Ti and ?-Ti Which can ensure the plasticity of the alloy and improve the high temperature strength and therma l stability of the alloy.At the same time,the addition of Zr element can also inhibit the precipitation of ? phase in the alloy and improve the comprehensive performance of the alloy.In fact,the addition of Zr in the field of high temperature titanium alloy is generally 0-4wt% and the content is low.In this paper,the microstructure and mechanical properties of high temperature titanium alloy under different high Zr content are explored to find out Effect on High Temperature Titanium Alloy.The alloys used in this paper are modified on the basis of the DSTi alloy developed by HIT to conduct the refining using a water-cooled crucible vacuum induction melting furnace(ISM)to control the other components and adjust the 4,6,8 and 10 wt% of Zr And then the relationship between the microstructure and properties of the titanium alloy and the Zr content was analyzed.The following results were obtained.For the original as-cast structure,EBSD and XRD and other means analysis,we can determine the four components of the alloy are basically ?-Ti,and with the Zr content increases,the grain has been a certain refinement,which The alpha phase change is small.And the tensile strength of the alloy increases with the increase of the Zr content,but the corresponding plasticity will gradually deteriorate.Through the 110 h and 750? cycle oxidation experiment,we can find that the oxidation and weight gain curves of the four alloys are in good agreement with the oxidation rule of the alloy,and it can be found that the addition of Zr has changed the oxidation kinetics of the alloy.When the Zr content is 4-8 wt%,the higher the Zr content,the better the oxidation resistance of the DSTi alloy.There were no significant differences in the surface of the four high te mperature titanium alloys after oxidation,both ?-Ti and Ti O 2.After the oxidation of the cross-section line scan results are similar,are the surface of the oxide film has a narrow peak of Al,in the oxide film inside the Zr and Ti peaks appear that the surface is Al oxide,the internal Zr and Ti Of the oxide.The change of the surface morphology and the change of the surface of the oxide surface after the high temperature oxidation of the four different compositions of the high temperature titanium alloy at 1min,15 min,2h,10 h and 30 h shows that the increase of the Zr content will make the material Of the antioxidant to a certain extent,increased.The effect of oxidation time and oxidation temperature on the properties of high temperature titanium alloy is that the longer the oxidation time,the worse the performance of the alloy;the higher the oxidation temperature,the worse the performance of the alloy.To a certain extent,the Zr content is increased,and the tendency of this property to deteriorate is smaller.On the basis of the above,we investigated the mechanism of the oxidation resistance of Zr to high temperature titanium alloy.The Zr content in the heat treatment is characterized by the increase of the grain size of the high temperature titanium alloy with different alloy composition.And the primary ? phase grown along the grain boundary shows a tendency to become thicker as the temperature increases.In the case where the Zr content is high,such as 8 and 10 wt%,there is a phenomenon in wh ich the particulate matter is precipitated along the original ? grain boundary,and this phenomenon is lowered as the alloy heat treatment temperature increases.As a result of the room temperature stretching,the alloy has the best mechanical properties w hen the solution is carried out at 950 ?.