| AZ91 magnesium alloy powder and Ba Ti O3 powder were used as raw material.Planetary-milling machinewas used for thinning initial AZ91 magnesium alloy powder.Hot pressing was used to prepare compact structure, good performance of AZ91 magnesium alloy block material.Orthogonal design method was used to establish experimental scheme.The effect of ball milling conditions such as milling time, milling rate and ball/powder weight ratio on milling results was studied. Experimental results showed that with the increase of the time, revolving speed and ball/powder weight ratio, the granularity of alloy powder decreases markedly. The ball milling parameters with rotational speed rate of 300r/min, milling time of 6h, ball/powder ratio of 20:1 was considered as the optimum ball milling technology. The effect of sintering temperature and sintering time on microstructure and microhardness was studied. When sintering temperature below 500℃, sintering process of the alloy is solid phase sintering, densification mechanism of the alloy is diffusion of atoms. When sintering temperature is above 500℃, sintering process of the alloy is liquid phase sintering, material diffusion caused by the liquid is faster than solid phase sintering.The density of sintered alloy was greatly improved.The optimum ball milling technology and hot pressing sintering process was used to prepare Ba Ti O3/AZ91 composite.Observed and studied the effect of Ba Ti O3 content on the microstructure and vicker microhardness of the composite. Ba Ti O3 ceramic phase distribution is diffuse in magnesium matrix when Ba Ti O3 ceramic content is low. Ba Ti O3 ceramic together tends to be serious when higher levels of Ba Ti O3 ceramic. In addition, the microhardness of composites first increases then decreases with the increase of Ba Ti O3. Transmission electron microscopy was usedto observe and research the interface between Ba Ti O3 and the magnesium substrate. There is obvious atom diffusion exists incomposite interface. At the same time, γ-Mg17Al12 phase precipitates near the interface.Due tothe high chemical stability of Ba Ti O3, interface reaction in melt magnesium it is hard to happen. The combination of the two phases is good and the interface is smooth without reaction layer. Multifunctional internal friction test was used to analysis the damping properties of composites with different composition.Dislocation damping, interface damping, grain boundary damping and piezoelectric-conductive dissipation damping mechanism that exists in composite were analysised. Whenamplitude is low, the damping values of five samples are very low.The damping value of the five samples increases with the improvement of amplitude and the damping performance of 10%Ba Ti O3/AZ91 is the best. Ba Ti O3/AZ91 composite damping performances the static hysteresis effect of amplitude. Itproves that dislocation damping is the main damping mechanism in Ba Ti O3/AZ91 composite at room temperature. |
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