(BNNT-BNNP)/(ZrB_2-SiC)超高温陶瓷复合材料形变强化及机理  

Strain Hardening Mechanism of(BNNT-BNNP)/(ZrB_2-SiC) Ultrahigh-Temperature Ceramic Composites

作　　者：刘卫卫[1] 张律[1] 岳春光[1] 苏佳楠 白朴存[2] 陈瑶[1] 

机构地区：[1]苏州大学,江苏苏州215021 [2]内蒙古工业大学,内蒙古呼和浩特010051

出　　处：《稀有金属材料与工程》2014年第12期3078-3081,共4页Rare Metal Materials and Engineering

基　　金：国家自然科学基金资助(51275326)

摘　　要：结合仪器化微米划入和仪器化微米压入对(BNNT-BNNP)/(Zr B2-Si C)超高温陶瓷复合材料的形变强化效果及机理进行研究,并利用光学金相显微镜(OM)、冷场发射扫描电镜(SEM)和高分辨透射电镜(HR-TEM)分别对压痕和划痕、样品断口形貌及显微组织结构进行分析。结果表明,(BNNT-BNNP)/(Zr B2-Si C)超高温陶瓷复合材料具有显著的形变强化效应,且随着(BNNT-BNNP)含量的增多,复合材料的形变强化效果愈加明显。复合材料在放电等离子烧结制备的冷却阶段,因其组成相热膨胀系数的显著差异,导致Zr B2相内形成大量位错,且以固定位错为主。这些固定位错将阻碍可动位错的运动,使复合材料塑性变形的阻力增大,导致复合材料呈现明显的形变强化效应。The strain-hardening behavior of （BNNT-BNNP）/（ZrB2-SiC） ultrahigh-temperature ceramic composites was determined by means of instrumented micro-scratch and micro-indentation. Also, the morphologies of scratch grooves and indentation marks, fracture surfaces and microstructure were investigated using Optical Microscopy （OM）, Scanning Electron Microscopy （SEM） and High Resolution Transmission Electron Microscopy （HR-TEM）. Results show that （BNNT-BNNP）/（ZrB2-SiC） composites exhibit a typical strain-hardening effect, which increases with more （BNNT-BNNP）. In the cooling process after sintering, highly localized residual stresses in the vicinity of nanofillers would be larger enough to create pre-existing dislocations due to significant difference in coefficient of thermal expansion between the constituent phases in the sintered composite. The sessile dislocations predominate in the pre-existing dislocations, and they are expected to contribute to form Orowan-loop-like configuration and to increase the resistance to plastic deformation of the composites, leading to the fact that strain-hardening occurs

关 键 词：超高温陶瓷 形变强化 位错 仪器化划入 仪器化压入 

分 类 号：TB332[一般工业技术—材料科学与工程]