原位反应浸渗法制备(B_4C+Ti)混杂增强Mg及AZ91D复合材料及其阻尼性能

Damping Capacities of(B_4C+Ti) Hybrid Reinforced Mg and AZ91D Composites Processed by In Situ Reactive Infiltration Technique

针对B_4C/Mg体系润湿性较差导致复合效率低下的问题,加入高熔点、不互熔金属Ti颗粒来改善该体系的润湿性,并成功利用原位反应浸渗法实现(B_4C+Ti)/Mg和(B_4C+Ti)/AZ91D复合材料的高效、低成本制备。对制备的(B_4C+Ti)/Mg和(B_4C+Ti)/AZ91D复合材料的微观组织、生成物相以及室温和高温阻尼性能进行了分析与表征。结果表明,制备温度对复合材料的微观组织和生成物相有较大的影响;随着制备温度的升高,原始颗粒之间的原位反应程度逐渐趋于完全,(B_4C+Ti)/AZ91D复合材料的微观组织逐渐由颗粒增强结构转变为网络互穿结构。(B_4C+Ti)/Mg和(B_4C+Ti)/AZ91D复合材料的室温和高温阻尼性能分别随着应变振幅和温度的升高而增强,主要作用机制为位错阻尼和界面阻尼机制。

Mechanical vibration causes lots of damage in automotive industry,machinery manufacturing and aerospace field.Noise control also causes much damage to human health.So it is of great significance to seek materials with high damping capacity to alleviate or eliminate mechanical vibration and noise.Pure Mg has the highest damping capacity among all of the commercial metal materials,but its low mechanical property impose restrictions on its pervasive application.Therefore,magnesium matrix composites reinforced with high mechanical property reinforcement can exhibit excellent damping capacity and mechanical property simultaneously,and this kind of material has attracted great attention and interest from researchers in recent years.A variety of preparation methods has been utilized to prepare magnesium matrix composites reinforced with different reinforcements.In situ reactive infiltration is a relatively new processing method to prepare metal matrix composites,which combines the advantages of in situ reaction synthesis and pressureless infiltration,and it has received increasing attention because of its cost-effectiveness,simplicity and high-efficiency,and near-net shaping capability.And by tailoring the relative density of preform,magnesium matrix composites with a high volume fraction of ceramic reinforcement can be obtained.In view of the poor wettability of B4C/Mg system leading to low efficiency of composite,Ti particulates with high melting point and immiscible with magnesium was added.And(B4C+Ti)/Mg and(B4C + Ti)/AZ91 D composites have been prepared successfully by in situ reactive infiltration method with high efficiency and low cost.Microstructure,phase composition and damping capacities of the as-fabricated composites were characterized and analyzed.Results showed that with increasing the preparation temperatures,the reaction between the starting materials is more complete,and the microstructure of(B4C + Ti)/AZ91 D composites tends to be interpenetrating networks from particle reinforced structure.The strain-dependent and temperature-dependent damping capacities of(B4C + Ti)/Mg and(B4C+Ti)/AZ91 D composites improve gradually with the increase of strain amplitude and temperature respectively,and the dominant damping mechanisms are dislocation damping and interface damping.