热处理对不同体积分数B_(4)C增强铝基复合材料组织和力学性能的影响

Effect of Heat Treatment on Microstructure and Mechanical Properties of Aluminum Matrix Composites Reinforced with Different Volume Fraction of B_(4)C

为了探究热处理对碳化硼颗粒增强铝基复合材料(B_(4)C/6061Al)性能的影响,课题组选择体积分数分别为10.0%,17.5%,25.0%和31.0%的B_(4)C增强铝基复合材料进行热处理(535℃保温5.0 h后温水淬,165℃时效4.5 h),采用扫描电子显微镜(SEM)观察复合材料的微观组织形态,并运用万能拉伸试验机测试其力学性能。研究结果表明:随着B_(4)C体积分数的增加,B_(4)C颗粒呈现聚集、破碎和剥落现象;热处理后的B_(4)C/6061Al复合材料的强度随着B_(4)C体积分数的增加而提升,延伸率随B_(4)C体积分数的增加则呈下降的趋势。B_(4)C体积分数为10.0%时,复合材料的屈服强度和抗拉强度分别是220.8和246.0 MPa,延伸率为11.76%;当B_(4)C体积分数增加至31.0%时,复合材料的屈服强度和抗拉强度分别为330.2和358.3 MPa,延伸率为2.18%。热处理之后,复合材料发生了动态再结晶,B_(4)C增强颗粒周围出现高位错密度区域。

In order to analyze the effect of heat treatment on the properties of boron carbide(B_(4)C)particle reinforced aluminum matrix composites(B_(4)C/6061Al),B_(4)C reinforced aluminum matrix composites with volume fractions of 100%,17.5%,25.0%,and 31.0%were selected for heat treatment(held at 535℃for 5.0 h,quenched with warm water,aged at 165℃for 4.5 h).The microstructure of the composites was observed by scanning electron microscope(SEM),and the mechanical properties were tested by universal tensile testing machine.The results show that with the increase of B_(4) C volume fractions,B_(4) C particles show aggregation,fragmentation and exfoliation.The strength and elongation of B_(4) C/6061Al composites after heat treatment increase with the increase of B_(4) C volume fraction.When volume fraction of B_(4)C is 10.00%,the yield strength and tensile strength of the composite are 220.8 and 246.0 MPa,respectively,and the elongation is 11.76%.When the volume fraction of B_(4)C increased to 31.00%,the yield strength and tensile strength of the composite are 330.2 and 358.3 MPa,respectively,and the elongation is 218%.After heat treatment,dynamic recrystallization occurs and high dislocation density regions appear around B_(4)C reinforced particles.