Thermal Deformation And Friction And Wear Behavior Of TiB_2P/2024Al Composite

For the30%Vol. TiB₂/2024Al composites fabricated by pressure infiltrationtechnology, high temperature compressive deformation and friction and wear behaviorwere studied. The experimental methods such as differential Thermal Analysis tester,universal electronic testing machine, friction and wear tester, scanning electronmicroscope （SEM）, transmission electron microscope （TEM） were employed. On thebasis of the study of the compressive deformation behavior and mechanisms of thecomposites, the best densification process parameters was obtained. The friction and wearbehavior and wear mechanism of the densification of composite were also studied.Study of high temperature compressive deformation has shown the compressivestress-strain curves of TiB₂/2024Al had three stages: elastic deformation stage, workhardening stage and strain softening stage. With the increasing of compressiontemperature increasing composites deformation resistance decreased as the strain raterose, and with increasing of strain rate deformation resistance of the composite graduallyincreased. The compression deformation limit of TiB₂/2024Al increased with theincreasing of temperature. Compression deformation limit of composites is the highest at0.014s^-1within the given strain rate range.Microstructure observation showed that: the lower in the temperature, the higherlevel in the degree of particle breaking. The higher in the strain rate, the worse in theinterface and matrix. Strain rate sensitivity coefficient m and deformation activationenergy Q calculations showed that because of the join of particle the plastic deformationability of matrix reduced, while also the value of m was low. The value of Q is higherthan aluminum because of particles obstruct. TEM observation showed that grain sizewas significantly small after compression deformation, and the main softeningmechanism is dynamic recovery.According to the study result in high-temperature deformation behavior of composite， we formulated the three-way constraints extrusion process parameters:deformation temperature was500℃and deformation rate was0.014s^-1.Deformed composite mechanical properties showed: for the composite materials ofdensification treatment, the tensile strength has improved, but the material elongationdecreasedStudy of the friction and wear of densification composite showed that: frictioncoefficient decreased with the increasing of load and increased with sliding speed. Thewear rate increased with the increasing of load and decreased with the increasing ofsliding speed. The stability of the friction process was improved with the increasing ofload and became worse with sliding speed. Densification improved friction and wearproperties significantly.SEM morphology of wear results showed that: The first stage the process of frictionwear mechanism was mainly oxidative wear, the second stage was the transition ofoxidative wear to adhesive wear, the steady state of wear process was the combination ofAbrasive wear and adhesive wear. In the lower load and sliding velocity abrasive wearmorphology was the main wear morphology; but in higher load and sliding velocityadhesive wear was the main.