Prepartion Of Ti-Al/B₄C Composite And Study Of Their Properties

Bron carbide ceramic has some properties,such as small relative density,high hardness, big intensity and wear resistance. Ti-Al order intermetallic compound is a kind of semi-ceramic material whose performance between metal and ceramics. It has overriding advantages as binder phase of ceramics including excellent inoxidability, resistance to sulfide, elevated temperature strength, small relative density and strong specific strength. Besause its atom ordered arrangement and compossibility of metallic bond and covalent bond fill the void of metal and ceramics in themechanical capacities. B4C ceramics substrate is wearable, high resistance and elevated temperature strength, Ti-Al intermetallic compound improved toughness. The composite material formed by B4C ceramics and Ti-Al intermetallic compound has outstanding themechanical capacities because of the advantages of them.Based on the above , In this paper, B4C ceramic was activated and sintered as substrate with Ti-Al intermetallic compound as a binder phase of B4C ceramics., Igredients Ti-Al/B4C uniform composite materials were prepared by controlling the composition and process. Preparation of composite materials, mechanical properties, microstructure, phase composition, toughening mechanisms were evaluated.The use of mechanical alloying process were prepared TiAl, Ti3Al powder. The organizational structure of the evolution of the microstructure in mechanical alloying and low temperature annealing process to be characterized and tested by XRD, TEM analysis methods. It was found that mechanical alloying is a process of repeated deformation, cold welding, upsetting, fracture process, The crystal structure and morphology of Ti-Al mixed powders changed a lot by strong mechanical milling. With the increase in milling time, Ti, Al diffraction peak intensity gradually decreased, a gradual increase in half-wide, The powder lost the original crystal morphology in the mechanical milling. The powder after 20 hours the milling completely converted into Ti-Al and Ti₃Al intermetallic compound after heat treatment 600℃.The feasibility of sintering was analysised by thermodynamic calculation of B₄C matrix and Ti-Al intermetallic compound. Preparation of composite materials have been identified by researching Ti-Al/B₄C performance of composite materials and micro-structure. Separately using a different content in two-phase TiAl and Ti₃Al and add as a binder in the composite material , its optimum contents were identified by physical properties of sintered comparison study. The results showed that: Ti-Al of the Department of IMC could increase in strength and toughness ofB₄C ceramic, the organic integration of the two can complement each other achieve toughening reinforcement . Experiment obtained the best ratio of composite material components for 20wt% Ti₃Al +80 wt% B₄C. Sintered at 1680℃,its bending strength 580.34MPa, fracture toughness is 8.07MPa·m^1/2, the hardness HRA94.1.