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Research on Damping Capacity of CuAlMn Alloy and CuAlMn Reinforced Magnesium Matrix Composites

Author: HanGang
Tutor: WuKun
School: Harbin Institute of Technology
Course: Materials Science
Keywords: A shape memory alloy Aging Reverse martensitic transformation Mg-based composite materials Damping properties
CLC: TB33
Type: Master's thesis
Year: 2010
Downloads: 57
Quote: 0
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Abstract


This thesis uses a vacuum melting method the prepared Cu11.5Al5Mn Cu10.5Al5Mn, Cu12Al6Mn three components of shape memory alloy, and the alloy solution treatment as well as different temperature and time of the aging treatment. This alloy is used as reinforcement, pure magnesium and AZ91 magnesium alloy as a matrix, the alloy is pulverized into crumbs, mechanical mixing, and then hot-pressing and hot extrusion method out of the volume fraction was 10%, 20%, 30% of the composite material. Using optical microscopy (OM) to study the different state of the CuAlMn alloy microstructure changes, and X-ray diffraction analysis of the phase composition of the alloy after solution and aging. Using differential calorimetry (DSC) analysis of the phase transition point of the alloy. Tensile test test room temperature mechanical properties of the alloy. Using mechanical dynamic thermal analyzer (DMA-Q800) test the performance of the CuAlMn alloy composite damping. Inverse martensitic transformation damping peak, and the the full Markov body damping state than the parent phase damping value high near 150 ℃ the prepared CuAlMn alloy during the heating process. Alloy after solution water quenching, will retain a lot of defects, and impede the movement of the phase interface Because of these shortcomings, the reverse martensitic transformation temperatures increase. Increase the rate with variable temperature phase transition increased damping peak reverse martensitic transformation point rise. Increase of the vibration frequency of the alloy phase change damping peak decreases, but the peak temperature is constant. Mahalanobis posture under a damping value of the alloy with the increase of the strain amplitude increases, and the damping value in the phase change region alloy with the increase in the strain amplitude and a slightly decreasing tendency. Based on the above phenomenon, we have come to the the thermoelastic martensitic alloy (inverse) change is a result of a variety of damping mechanisms together. The study found that after the aging CuAlMn alloy, the alloy has a good anti-martensite stabilization performance. Lower temperatures under aging martensite morphology changes, increase in the degree of order, organization since better coordination; higher temperature aging, there will be a second phase γ2 precipitation, martensite orientation relationship becomes complicated, orderly decreased. The martensite morphology changes is an atomic diffusion process, with increasing temperature, the acceleration of the element diffusion speed, the time of this process occurs gradually shortened. Alloy aged at 200 ℃ 2h after its phase change damping peak achieve the best, while tensile strength, elongation to achieve the best. CuAlMn Hop Jinjiaruji body composite damping performance study shows that, room temperature CuAlMn alloy joined pure magnesium matrix, its damping no significant change, a slight decline trend; but added AZ91 alloy base body time, its damping have great improve, and with increasing volume fraction, damping value increases greatly. While in the damping - Temperature compose Online, the damping of the two composites is increased with increasing temperature. But the expected in CuAlMn phase change region will produce the high damping and does not appear, may be due to hindered CuAlMn alloy material generates some variation in the preparation process due to the phase change. On the basis of the existing experimental conditions, using hot pressing and hot extrusion method, and the experimental results of this expectation is difficult to achieve.

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