在超声场下,以Al-Ti为反应体系,采用熔体直接反应法原位合成Al3Ti/ADC12复合材料.研究Ti加入量、超声时间以及功率对复合材料的显微组织和力学性能的影响.结果表明:随着超声功率的逐渐增加,Al3Ti颗粒尺寸变得愈加细小,分布也变得更为均匀;并且Ti的加入能够细化基体组织中的α-Al相,使其由原来的粗大树枝状逐渐转变为细小枝晶状、蔷薇状甚至近球状.然而,随着超声时间的增加,超声效果会出现先加强后减弱的趋势.Al3Ti/ADC12复合材料的力学性能变化趋势与其组织变化趋势相一致,当Ti添加量为3％(质量分数)、超声功率为1.5kW、超声频率为20kHz、超声时间为6min时,其综合性能较好,抗拉强度达到247.34MPa,伸长率达到2.31％,比未施加超声的复合材料分别提高了21.3％和50.0％.%Aluminum matrix composites reinforced by in-situ Al3Ti particles were successfully synthesized from an Al-Ti system via a direct melt reaction.The influences of Ti additions,ultrasonic time and power on the microstructure and mechanical property of composites were systematically investigated.The results show that the Al3Ti particles are refined obviously and the distribution also becomes more uniform with the increase of ultrasonic power.Meanwhile,the addition of Ti refines the α-Al dendrite phases in the matrix,which gradually changes from the original coarse to fine branch crystals,rose-like or nearly spherical.However,results also show that the size of Al3Ti particles decreases to a minimum value and then increases with the increase of ultrasonic time.The trends of the mechanical properties are consistent with the microstructures of the Al3Ti/ADC12 composites.The optimum parameters of the composite are 3％Ti (mass fraction) content,1.5kW ultrasonic power,20kHz ultrasonic frequency and 6min ultrasonic time.Accordingly,the tensile strength and elongation of the composite synthesized reach to 247.34MPa and 2.31％ respectively,increasing by 21.3％ and 50.0％ compared with the unmodified alloy.
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