Research On Damping Capacity Of Cualmn Alloy And Cualmn Reinforced Magnesium Matrix Composites

Three kinds of alloys with different compositions were fabricated by vacuum induction furnace. The alloys were soluted and then aging at different temperatures. The Cu11.5Al5Mn and Cu12Al6Mn allovs were chosen as reinforcement, the commerical pure Mg and AZ91 alloys were used as the matrix, the CuAlMn/Mg,CuAlMn/AZ91 with volume fraction 10%,20%,30% were fabricated by hot pressure and extrusion. The chemical composition was tested by X-ray Fluorescence Spectrometer(XRF). The microstructures of the CuAlMn alloys after different treatment were observed by Optical Micrograph(OM). The phase construction of the alloys after solution and aging was tested by X-Ray Diffractometer(XRD). The phase transformation temperature of the alloys was analysised by Differential Scanning Calorimetry(DSC). The damping capacities were measured by dynamic mechanical analyzer(DMA).The results show that the alloys appear a martensite inverse-transformation damping peak at about 150℃and the damping in the martensite condition is higher than the parent phase. The inverse transformation temperature(As) of the alloys increases after quenching into water because there are much defects that hinder the movement of martensite and varient interfaces. The As and the transformation damping value increase with the increase of the heating temperture rate. The transformation damping decreases with the increase of the frequency and the strain amplitude. So we make the conclusion that there are several damping mechanisms that effect on the transformation zone.The research results of the aging alloys show that the CuAlMn alloys have good resistance ability to the martensite stability. When the alloys were aging at lower temperature, the martensite structure changes and the incoordination of the structure is better. After aging at higher temperature, the second phaseγ2 is preciptated and the orientation relationship of the varients is complicated. These variations is a process which accompanies by the atom diffusion and it speeds up with the increasing temperature. After the alloys were aging at 200℃for 2h. the damping peak reached to the highest value. Simultaneously the ultimate strengh and the elongation also reached to the best.The CuAlMn alloys were added as reinforcment to the pure Mg and AZ91 matrix. The result of damping measurement shows that in the room temperature, the damping of GuAlMn/Mg have no obvious variation related to the pure Mg matrix and the damping value of GuAlMn/AZ91 increases obviously with the increase of the reinforcement volume fraction. When the temperature increases, the damping of the two composites increase.But there is no martensite inverse-transformation damping peak in the composites. Maybe it is because that the CuAlMn alloys have some changes during the pressure and extrusion process that rejects the transformation of the alloys. So under the existing experimental conditions, we can't get the prospective experimental result.