新型三元层状硼化物Cr4AlB4的物相稳定性和力学行为分析  

Analysis on Phase Stability and Mechanical Property of Newly-discovered Ternary Layered Boride Cr4AlB4

作　　者：齐欣欣 宋广平[1] 尹维龙[1] 王明福 赫晓东[1] 郑永挺[1] 王荣国[1] 柏跃磊[1] QI Xin-Xin;SONG Guang-Ping;YIN Wei-Long;WANG Ming-Fu;HE Xiao-Dong;ZHENG Yong-Ting;WANG Rong-Guo;BAI Yue-Lei(National Key Laboratory of Science and Technology on Advanced Composites in Special Environments,Harbin Institute of Technology,Harbin 150080,China;Beijing Power Machinery Research Institute,Beijing 100074,China)

机构地区：[1]哈尔滨工业大学特种环境复合材料技术国家级重点实验室,哈尔滨150080 [2]北京动力机械研究所,北京100074

出　　处：《无机材料学报》2020年第1期53-60,共8页Journal of Inorganic Materials

基　　金：国家自然科学基金(51972080);黑龙江省自然科学基金重点项目(ZD2017011);中国博士后科学基金(2017T100230)~~

摘　　要：Cr4AlB4是一种近期发现的三元层状硼化物MAB相陶瓷。该材料可形成具有保护性的氧化膜,在高温结构材料领域有巨大应用潜力。本工作采用基于第一性原理的“线性优化法”和“键刚度”理论模型分别研究了Cr4AlB4的物相稳定性和力学行为。声子谱中没有虚频出现,表明Cr4AlB4具有本征稳定性。而与其它Cr-Al-B系内的竞争相相比,Cr4AlB4具有最低的能量,表明其在热力学上也是稳定的。采用“键刚度”模型对化学键刚度的定量计算显示,Cr4AlB4中Cr和B以及B和B原子之间形成了强共价键,而Cr和Al原子则形成相对较弱的Cr-Al(625 GPa)和B-Al(574 GPa)键。Cr4AlB4可以看成是由强共价键紧密连接在一起的Cr-B结构单元,被弱Cr(B)-Al键分割而成的层状结构,与MAX相结构类似。Cr4AlB4具有类似于MAX相的高损伤容限和断裂韧性。As newly-discovered member of the MAB phases,Cr4AlB4 has much potential for high-temperature structural applications due to possible formation of a protective oxide scale.By use of“linear optimization procedure”and theoretical model of“bond stiffness”based on first-principle calculations,the phase stability and mechanical behavior of Cr4AlB4 were investigated.No imaginary frequencies in phonon dispersion indicate the intrinsic stability.The lower energy as compared with the set of other competing phases also shows the thermodynamic stability.Based on the quantificationally calculated bond stiffness by use of the model of“bond stiffness”,strong covalent bonding is present between Cr and B atoms as well as B and B atoms,while the Cr-Al(625 GPa)and B-Al(574 GPa)bond is relatively weak.It follows that Cr4AlB4 can be described as layered structure of strong covalently bonded Cr-B blocks interleaved by Al atomic planes where the bonding is relatively weak,similar to the well-known MAX phases,which demonstrates the similar damage tolerance and fracture toughness of Cr4AlB4 with the MAX phases.

关 键 词：MAB相 密度泛函理论 物相稳定性 力学性能 

分 类 号：TQ134[化学工程—无机化工]