Of Fe <sub> 3 </ Sub> Al Bulk Material Sintered And Performance

Fe₃Al intermetallics are new types of inexpensive material whose properties are between metal and ceramic.The properties of antioxidation,sulfuring property,nitric acid corrosive resistance,high temperature strength and high temperature creep are better than most of metal material,with its thermal conductivity and plasticity are better than ceramics.Fe₃Al intermetallics have long range ordered structure,which prevent the dislocation motion and atomic diffusion influencing its plasticity,so as a type of high temperature structural material is limited.On the Friction and Wear application,it is not critical for the plasticity of the material,but the strength and hardness and the work hardening rate is demanded,so Fe₃Al intermetallics have great application potential in the tribology fields.In this paper,Fe₃Al powder is fabricated by mechanical alloying and annealing treatment,and the Fe₃Al bulk materials are prepared by vacuum hot-press sintering.The microstructure,physical and mechanical property, friction and wear property,oxidation and corrosion resistance are discussed.The content of Al in Fe₃Al and the influence of Ti,Ni,Cr on the properties of Fe₃Al bulk material are researched in this paper.The research results are listed as fallows.(1) Fe₃Al bulk material can reach to a relative density of higher than 97%,with low ordered B2 structure as the main phase,and with small amount of dispersed Al₂O₃ particles.The average grain size is about 600～800nm.(2) The room temperature mechanical properties of Fe₃Al bulk material are largely improved.The room temperature bending strength is about 1000～1400MPa, compressive yield strength is about 1200～1800MPa,compressive strain is about 10%～15%,and the hardness is about HRC 55～60.The content of Al in Fe₃Al and the alloying elements influence the mechanical properties of the materials greatly. (3) Fe₃Al intermetallics have excellent wear resistance,and alloying elements improve the wear resistance at different degree.Under low load Plasticity deformation occurs on the worn surface of the material with the micro-cutting and micro-ploughing.Cracks appear and expand rapidly under stress concentration under high load,finally inducing fatigue fracture,which spalling in the form of flake structure.(4) Fe₃Al prepared by hot pressing sintering under 1100℃with good oxidation resistance,but decreasing above 1300℃.Fe₃Al base material doping with Cr can promote the formation ofα-Al₂O₃ film which improves oxidation resistance of the material,doping with Ti in the Fe₃Al can refine grain size and improve oxidation resistance of the material obviously.