High Damping Capacity Of Al Matrix Composites Fabricated By Accumulative Roll Bonding

In recent years,Aluminum matrix composites(AMCs)have been widely concerned because of their high strength,high rigidity and low density.However,the research on AMCs is mainly focused on the light and high strength,and its damping performance is very little.In this paper,the Li6.75La3Zr1.75Nb0.25O12(LLZNO)ceramic particles and M2052(Mn-Cu)metal particles with high damping performance near the room temperature were selected as the reinforcement phase and the Accumulative roll bonding(ARB)method was exploited to fabricate second phase reinforced Al composites,which is expected with excellent mechanical properties and room temperature damping capacity by using the intrinsic damping and dispersion strengthening effect of hard particles.At the same time,the addition of the second phase increases the dislocation density and introduces a large number of particle/matrix interfaces,which can also effectively improve the damping of composite materials.In this paper the effects of preparation techniques such as rolling process,heat treatment and the addition of the second phase particles were evaluated systematically by internal friction(IF),tensile test and surface microhardness measurement as well as XRD,SEM and EDS measurement,respectively.The main results are concluded as follows:(1)ARB process is solid-state composite at room temperature.The preparation techniques is simple and no need to consider the difference of the melting point,the density and the wetting angle.The ARB process has been employed as a novel technique to fabricate AMCs,where pores-free composites and a uniform distribution of reinforcement particles in the Al-matrix can be realized.ARB method based on a severe plastic deformation has been used to fabricate ultrafine-grained materials.So the mechanical properties of AMMCs which fabricated by ARB process is influenced by the hard phase.the boundary hardening and dislocation hardening.(2)In order to fabricate high damping/strength metal matrix composites,in this paper.10wt%hard ceramic particulates LLZNO with high damping capacity have been introduced into Al-matrix by ARB method.LLZNO particles were uniformly dispersed in Al-matrix he interface was well bonded.after 10 ARB cycles,The ultimate tensile strength of the LLZNO/Al composites reached 132 MPa(2.5 times that of the pure Al)and the hardness is 66 HV(2.4 times that of pure Al).When having a heat treatment,the composite had a larger elongation of about 29%.The maximum damping capacity achieved as high as 0.009,which was 4.5 times that of pure Al.A heat treatment has little effect on damping property.(3)The Mu-Cu/Al composites were prepared by the accumulative rolling method.and the mass fraction of Mu-Cu was 20%.After 13 passes,the Mn-Cu particles were harmoniously distributed in the matrix,and no intermetallic compounds were formed.The energy spectrum analysis showed good interfacial bonding.The maximum tensile strength of Mn-Cu/Al composites is 110 MPa(2.1 times that of pure Al).After a treatment at 420 ?,the strength and hardness decreased,but the damping(Q-1=0.01)and plasticity(20%)were improved obviously.The resistivity of Mn-Cu/Al composites is 2.64??·cm.which is slightly lower than that of pure aluminum,but much higher than that of several common aluminum alloys.(4)Compared with LLZNO ceramic particles,metal Mn-Cu particles shows a better adhesion with Al matrix.In the case of high mass fraction,only the lower deformation and room temperature rolling Mn-Cu particles can be combined with aluminum.However,the particle size of Mn-Cu particles is larger(10 ?m)which is about 5 times of LLZNO particles,so its enhancement effect on the composite is not as LLZNO particles.