| Laminated metal composites have received widespread attention in the world in recent years.Aluminum alloys are widely used in the research and industrial field of laminated metal composite sheets because of their low density,good corrosion resistance,good plastic deformation ability and strong bonding ability with heterogeneous materials.Based on 1060 aluminium alloy,the rolling experiments of Al1060/TU2,Al1060/AZ31B,Al1060/TC4 and Al1060/AZ31B/TC4 laminated metal composite sheets were carried out.The microstructures were tested by OM,XRD and SEM,mechanical properties such as elongation,shear,bending,hardness,and impact were investigated to study the effects of different rolling reduction rates and diffusion annealing temperatures on the microstructure and properties of layered metal composite sheets.The main research contents and conclusions are as follows:(1)The hot rolling and diffusion annealing tests of Al/Cu composite plates with different rolling reduction rates and annealing temperatures were carried out by hot roll rolling composite method.The influence of different process parameters on the microstructure and mechanical properties of composite plates was analyzed.When rolling reduction is less than 70%and annealed,mechanical bonding is the main mode of Al/Cu composite sheet,and metallurgical bonding is the main mode when rolling reduction is more than 70%.With the increase of reduction rate,the bonding interface of Al/Cu composite plate will be smoother and tighter,and the shear strength and tensile strength will increase first and then decrease.As the increase of diffusion annealing temperature,the diffusion layer formed on the interface becomes thicker and thicker.When the annealing temperature reaches above 300℃ or at a higher reduction rate,intermetallic compounds will be formed.The intermetallic compound CuAl2 is near the substrate Al side,Cu9Al4 is near the substrate Cu side,and CuAl is between CuAl2 and Cu9Al4.Diffusion annealing at 300℃,the interface bonding is better when the reduction rate is 70%,the shear strength reaches a maximum of about 112.94 MPa,and the tensile strength reaches 300.35 MPa.(2)Al/Mg/Al composite plates with rolling reduction of 45%,62%,73%and 83%were prepared by hot roll rolling.Then the diffusion annealing of the composite plates at 200℃,250℃ and 300℃ was carried out.The effects of process parameters on the structure and properties of the composite plates were studied by using relevant experimental equipment.The results show that with the increase of the reduction rate,the composite plate is gradually transformed into a strong metallurgical bond by mechanical bonding,and the diffusion layer at the interface of the two metals is gradually thickened.The intermetallic compound on the Al base side is a mixture of Al3Mg2 and MgAl2O4;the intermetallic compound near the Mg base side is Mg17Al12;and the middle is Al3Mg2.When the reduction rate is 62%,the Al/Mg binding boundary begins to appear as a "wavy" line.When the reduction rate is increased to 73%,the undulation of the "wavy" line increases,and the shear slope exhibits a certain angle.When the reduction rate was 83%,the magnesium plate of a part of the intermediate layer was broken.(3)Under unannealed condition,elongation of Al/Mg/Al composite sheet increases with the increase of reduction rate,tensile and flexural strength first increases and then decreases with the increase of reduction rate.The tensile strength reaches 254.45 MPa and the flexural strength reaches 271.94 MPa at 73%reduction rate.At 250℃ diffusion annealing,the shear strength of the composite sheet increases first and then decreases with the increase of the reduction rate,and reaches a maximum value of 144.00 MPa at the 73%rolling reduction rate.(4)Al/Ti/Al composite sheets with a reduction rate of 53%,62%,71%and 89%were prepared by hot rolling,and then the composite sheets were diffused at 200℃,300℃ and 400℃.The structure and properties of the composite plates with different process parameters were analyzed by metallographic microscope and scanning electron microscope.The results show that under the action of rolling deformation,the surface of the titanium alloy has cracks in the thickness direction,and the aluminum alloy sheet with excellent plasticity is extruded into the rough surface and crack of the titanium alloy sheet to increase the mechanical combination strength of the aluminum sheet and the titanium sheet.During the annealing process,the aluminum plate and the titanium plate are mutually diffused to form a variety of intermetallic compounds.The interfacial diffusion thickness increases with the increase of annealing temperature.The thickness of unannealed,200℃,300℃ and 400℃,are 1.2 μm,1.8μm 2.4 μm and 2.7 μm,respectively.(5)The experiments of Al/Mg/Ti/Mg/Al composite plates with different reduction rates and diffusion annealing were carried out.The metallographic,scanning and interfacial hardness of the composite plates with different processing parameters were analyzed.For Mg/Ti composite interface,when the reduction rate is 44%,there is a certain width gap at the interface.When the reduction rate reaches 74%,the gap has disappeared.Some magnesium alloys extend from the matrix to the gap on the surface of titanium alloy.With the rolling reduction rate increasing to 81%,the gap opening on the surface of titanium alloy increases,more magnesium alloys are squeezed into the gap,and a strong mechanical bond is formed between magnesium alloy and titanium alloy.After diffusion annealing,the residual stress in the composite plate is eliminated and the interface is restored,which makes the hardness decrease obviously. |
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