Study On Mechanical And Tribological Properties Of Ti₂AlNb-based Self-lubricating Composites

Ti₂AlNb-based alloys have excellent mechanical properties and are widely used in many fields,but their poor tribological properties limit the application of the alloy under extreme operating conditions such as high-speed heavy load and high and low temperature alternation.Therefore,development Ti₂AlNb-based self-lubricating composites is the key to the further application of this alloy under extreme working conditions.In this paper,the Ti₂AlNb-based alloy is taken as the research object.In order to improve the tribological properties of the Ti₂AlNb-based alloy without losing its mechanical properties,the solid lubricant Ag is introduced as the lubricating phase of the composite to improve the tribological properties of the material,and the ceramic particles TiB2 are added As the reinforced phase of the composite,its mechanical properties are improved to achieve the harmonization and unification of the mechanical properties and tribological properties of the composite.The effect of different amounts of lubricating phase Ag on the tribological and mechanical properties of Ti₂AlNb-Ag composites was studied.The results showed that: at room temperature and 500℃,the lubricating phase Ag significantly improved the tribological properties of the composite,The Ag content between 10 wt.% and 15 wt.% has the best tribological properties.The room temperature friction coefficient and wear rate of Ti₂AlNb-10 wt.%Ag composites were reduced by 45.1% and 49.6% compared with the matrix;the friction coefficient and wear rate of high temperature at 500℃ were reduced by 44.1% and 51.8%,respectively.Comprehensive microscopic wear morphology analysis shows that the complete lubrication film formed by Ag migration and spreading at the friction interface of the composite material during the friction process has low shearing effect,which greatly reduces the friction coefficient and wear rate.In order not to damage the mechanical properties of Ti₂AlNb-based composites,the Ti₂AlNb-10 wt.%Ag composite system was optimized through research,on the basis of which different amounts of TiB2 were added,and the TiB2 content was studied on the room temperature of Ti₂AlNb-Ag-TiB2 composites And 500℃ high temperature tribology and mechanical properties,the results show that: after adding TiB2,the friction coefficient of the composite material does not change much,the wear rate decreases slightly with the increase of TiB2 content,enhance the mechanical properties of the composite material TiB2 Performance has a significant improvement effect.The room temperature compressive strength and yield strength of Ti₂AlNb-10 wt.%Ag-5 wt.% TiB2 composite material are 8% and 14.7% higher than those of Ti₂AlNb-10 wt.%Ag material respectively;the high temperature compressive strength and yield at 500℃ The strength was increased by 28.8% and 43.6% respectively.The results show that Ti₂AlNb-10%Ag-5%TiB2 composite has both excellent mechanical properties and tribological properties.