The Preparation Of Three-dimensional Network Ti₂AlC/TiAl Composites And Their High-temperature Friction And Wear Behavior

TiAl alloy is recognized as a new generation of high-temperature light alloy because of its low density,high specific strength,and good high-temperature oxidation resistance.However,its poor fracture toughness at room temperature,low plasticity,and high friction coefficient make TiAl alloy Parts made of alloys are more likely to fail in complex and harsh working environments.Therefore,people have introduced reinforcement phases to TiAl alloys to improve the performance of TiAl alloys.In this paper,TiAl alloy powder and Ti₂AlC powder were used as raw materials to obtain composite materials with different reinforcement phase volume fractions by mechanical ball milling and vacuum hot-pressing sintering.Friction and wear experiments,the following conclusions were obtained:?1?In the fired composite material,the reinforced phase in the composite with20vol%reinforced phase mainly exists as a three-dimensional network structure,and the reinforced phase in other contents exists in the form of particles or the reinforced phase forms a coarse network-like structure;In terms of mechanical properties at room temperature,the hardness is the highest in the reinforced phase content of40vol%,the flexural performance is the best in the composite material with the reinforced phase content of 20vol%,and the compression performance is the composite material with the reinforced phase content of 20vol%and the TiAl matrix The closest and higher than several other composite materials.?2?The 800? cyclic oxidation resistance of the composite material is higher than that of the TiAl matrix,and with the increase of the content of the reinforcing phase,the cyclic oxidation resistance of the composite material is enhanced,and the oxidized weight is reduced.TiAl-based composites are more seriously oxidized.As the oxidation temperature decreases,the weight gain of oxidation also decreases;the oxide film of TiAl alloy is mainly composed of Ti O₂ and Al₂O₃,while the oxide of the composite material is mainly generated by the reinforcement phase.The oxide film formed by the mixing of Ti O₂ and Al₂O₃ produced by bulk Ti O₂ aggregates and TiAl matrix with the Al₂O₃ produced by the reinforcement phase,the distribution of Ti O₂aggregates becomes denser as the content of the reinforcement phase increases.?3?At 800?,the friction coefficient of TiAl alloy is higher than that of composite materials with 10vol%,20vol%,and 30vol%reinforced phase content.Among the three composite materials,the friction coefficient with 20vol%reinforced phase content is the lowest and wear-resistant Better,and the friction coefficient is more stable,and the friction coefficient of TiAl alloy and the other two composites increases with the increase of the experimental time;the composite with 20vol%reinforced phase content has the highest friction coefficient at 25? and 200? The coefficient of friction is lower than the coefficient of friction at 25?,while the coefficients of friction at 400?,600?,and 800? are similar and lower than those at200?.In summary,the composite material with the Ti2AlC content of 20 vol%was determined to have the best overall mechanical properties and the lowest friction coefficient.