20vol%体积分数纳米Al_(2)O_(3)颗粒增强铝基复合材料的高温压缩性能  

High-temperature compressive properties of 20vol%volume fraction nano-Al_(2)O_(3) particles reinforced aluminum matrix composite

作　　者：李玄 赵科[1,2] 刘金铃[1,2] LI Xuan;ZHAO Ke;LIU Jinling(School of Mechanics and Aerospace Engineering,Southwest Jiaotong University,Chengdu 611756,China;Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province,Southwest Jiaotong University,Chengdu 611756,China)

机构地区：[1]西南交通大学力学与航空航天学院,成都611756 [2]西南交通大学应用力学与结构安全四川省重点实验室,成都611756

出　　处：《复合材料学报》2023年第2期1118-1128,共11页Acta Materiae Compositae Sinica

基　　金：四川省重点研发项目(2020YFG0140)。

摘　　要：为提高铝基材料的高温力学性能以满足其在573 K以上用于航空航天装备结构件的性能需求,采用高能球磨结合真空热压烧结工艺制备了体积分数高达20vol%的纳米Al_(2)O_(3)颗粒(146 nm)增强铝基复合材料,对其微观结构和高温压缩性能进行了研究。结果表明:纳米Al_(2)O_(3)颗粒均匀分散于超细晶铝基体中,且复合材料完全致密;该复合材料具有优异的高温压缩性能:应变速率为0.001/s时,473 K时压缩强度高达380 MPa,即使673 K时依然高达250 MPa,比其他传统铝基材料提高至少1倍;通过对其流变应力进行基于热激活的本构模型拟合可以发现,该复合材料具有高的应力指数(30)和表观激活能(204.02 kJ/mol)。这是由于高体积分数纳米颗粒能够有效钉扎晶界,并与铝基体形成热稳定的界面结合,显著提高复合材料的组织热稳定性,而且在变形过程中与晶界有效阻碍位错运动,显著提高复合材料的热变形门槛应力(在473~673 K时为190.6~328.4 MPa),其热变形过程可以由亚结构不变模型进行解释。To improve the high-temperature mechanical properties of aluminum-based materials with the aim of satisfying application requirements for the structural components in aerospace above 573 K,a novel aluminum matrix composite reinforced with 20vol%volume fraction nano-Al_(2)O_(3)particles(146 nm)was prepared via high energy ball milling followed by vacuum hot pressing,and its microstructures and high-temperature compressive properties were investigated.The results show that,nano-Al_(2)O_(3)particles are uniformly distributed in the ultrafinegrained Al matrix,and the resultant composite is fully densified.The composite exhibits superior high-temperature compressive properties:As the strain rate is fixed as 0.001/s,the high-temperature compressive strength reaches380 MPa at temperature of 473 K,still maintains a high value of 250 MPa when the temperature increased to 673 K,which is at least onefold higher than that of traditional Al-based materials.By establishing constitutive model based on thermal activation,it is also found that the composite shows high stress exponent which is 30 and high apparent activation energy which is 204.02 kJ/mol.This may be attributed to the addition of high volume fraction nanoparticles into Al matrix which not only anchors Al grain boundaries and enables thermal stable interface between nanoparticles and the Al matrix and thus significantly enhance the thermal stability of the microstructure,but also can impede the dislocation motion effectively as well as Al grain boundary,thereby increasing the threshold stress for hot deformation which ranges from 190.6 MPa to 328.4 MPa as the temperature is in the range of 473 K to 673 K.The hot deformation process of this composite can be properly explained by substructure invariant model.

关 键 词：铝基复合材料 纳米Al_(2)O_(3)颗粒 高温压缩强度 门槛应力 亚结构不变 

分 类 号：TB331[一般工业技术—材料科学与工程]