B_(4)C-Al_(2)O_(3)复合陶瓷的增韧机理  

Toughening Mechanism of B_(4)C-Al_(2)O_(3)Composite Ceramics

作　　者：张巍 张杰[1,2] ZHANG Wei;ZHANG Jie(Shenyang National Laboratory for Materials Science,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China;School of Materials Science and Engineering,Shenyang University of Technology,Shenyang 110870,China)

机构地区：[1]中国科学院金属研究所,沈阳材料科学国家研究中心,沈阳110016 [2]沈阳工业大学材料科学与工程学院,沈阳110870

出　　处：《材料研究学报》2024年第8期614-620,共7页Chinese Journal of Materials Research

基　　金：辽宁省自然科学基金(2022-MS-013);中国科学院金属研究所自主部署项目(E255L401);沈阳材料科学国家研究中心青年人才项目(E21SL412)。

摘　　要：在碳化硼(B_(4)C)陶瓷中加入第二相Al_(2)O_(3),研究其对B_(4)C陶瓷断裂韧性的影响和B_(4)C-Al_(2)O_(3)复合陶瓷的增韧机理。结果表明,在B_(4)C陶瓷中引入第二相Al_(2)O_(3)使B_(4)C陶瓷的断裂韧性提高。Al_(2)O_(3)加入量为40%(质量分数)的B_(4)C-Al_(2)O_(3)复合陶瓷,其断裂韧性达到最大值4.96 MPa·m^(1/2)。B_(4)C-Al_(2)O_(3)复合陶瓷的增韧机理是,在B_(4)CAl_(2)O_(3)复合陶瓷中裂纹的扩展过程中Al_(2)O_(3)晶粒形成了解理结构。这种解理结构,延长了裂纹扩展的路径和消耗了部分裂纹扩展能。同时,Al_(2)O_(3)晶粒与B_(4)C晶粒之间因热膨胀失配而产生了残余应力。虽然B_(4)C晶粒内的压应力有利于抑制裂纹的扩展,但是B_(4)C晶粒与Al_(2)O_(3)晶粒的相界处产生的张应力在一定程度上弱化相界的结合而使部分裂纹在扩展过程中沿晶扩展出现偏转,从而使B_(4)C-Al_(2)O_(3)复合陶瓷的断裂韧性提高。B_(4)C ceramics has extremely high hardness,but its fracture toughness is low.In order to improve the fracture toughness of B_(4)C ceramics,the effect of introducing the second phase Al_(2)O_(3)on the fracture toughness of B_(4)C ceramics is studied,and the toughening mechanism of B_(4)C-Al_(2)O_(3)composite ceramics is explored.The results indicate that the addition of Al_(2)O_(3)as the second phase can improve the fracture toughness of B_(4)C ceramics.Among others,the fracture toughness of B_(4)C-Al_(2)O_(3)composite ceramics with 40%Al_(2)O_(3)reaches a maximum value of 4.96 MPa·m^(1/2).The toughening mechanism of B_(4)C-Al_(2)O_(3)composite ceramics is that Al_(2)O_(3)grains experience cleavage cracking during the crack propagation,increasing the path of crack propagation;thus,part of crack propagation energy is consumed.Meanwhile,residual stress is generated between Al_(2)O_(3)grains and B_(4)C grains due to their thermal expansion mismatch.On the one hand,the compressive stress inside B_(4)C grains is beneficial for inhibiting crack propagation.On the other hand,the tensile stress generated at the phase boundary between B_(4)C grains and Al_(2)O_(3)grains weakens the bonding of the phase boundary to some extent,leading to some cracks propagating along the phase boundary during the propagation process;therefore,some cracks are deflected,and so the fracture toughness of B_(4)C-Al_(2)O_(3)composite ceramics is improved.

关 键 词：无机非金属材料 断裂韧性 B_(4)C-Al_(2)O_(3)复合陶瓷 解理结构 热膨胀失配 裂纹扩展 

分 类 号：TB321[一般工业技术—材料科学与工程]