熔渗制备B_4C-MgSi复合材料的熔渗动力学、微观结构及力学性能  

Infiltration kinetics, microstructure and mechanical properties of B_4C-MgSi composite fabricated by melt infiltration

作　　者：邹志欢 曾凡浩[1,2] 刘吉安 李漪 古一[3] 张福勤[1,2] ZOU Zhihuan;ZENG Fanhao;LIU Ji’an;LI Yi;GU Yi;ZHANG Fuqin(State Key Laboratory of Powder Metallurgy,Central South University,Changsha 410083,China;The National Key Laboratory of Science and Technology on High-Strength Lightweight Structural Materials,Changsha 410083,China;School of Materials Science and Engineering,Central South University,Changsha 410083,China)

机构地区：[1]中南大学粉末冶金国家重点实验室粉末冶金研究院,长沙410083 [2]轻质高强结构材料国防科技重点实验室,长沙410083 [3]中南大学材料科学与工程学院,长沙410083

出　　处：《粉末冶金材料科学与工程》2018年第3期252-260,265,共10页Materials Science and Engineering of Powder Metallurgy

基　　金：国家自然科学基金项目(51301210)

摘　　要：采用真空熔渗法在1000℃的温度下向多孔碳化硼基体中熔渗Mg-Si共晶合金制备碳化硼-镁基合金(B_4CMgSi)复合材料。理论计算表明,1000℃下,熔融Mg在多孔碳化硼中的熔渗深度随时间延长而增加,熔渗速度先快后平稳,60min可达2.2cm以上,相同条件下MgSi合金比纯Mg渗透得更深。采用X射线衍射仪对B_4C-MgSi复合材料的相组成结构进行分析,采用SEM对B_4C-MgSi复合材料的显微组织结构进行观察,并对B_4C-MgSi复合材料的力学性能进行研究。结果表明:B_4C-MgSi复合材料主要由B_4C、SiC、Si和Mg2Si相组成,B_4C-MgSi复合材料熔渗前具有许多连通的孔隙,熔渗后孔隙被充分填充,致密度达到98%以上。复合材料的洛氏硬度高达71.3±3.3HRA,抗弯强度为285.81±11.32MPa,断裂韧性比单一碳化硼提高1倍,达到5.27±0.53MPa·m1/2。B_4C-MgSi复合材料的断裂方式是一种脆性断裂与韧性断裂相结合的混合断裂模式,不再是碳化硼基体单一的脆性断裂。B4C-MgSi composites were prepared by vacuum perpetration with infiltrating porous B4C substrates at 1 000℃with a Mg-Si eutectic alloy.The theoretical calculation shows that at the temperature of 1 000℃,the infiltration depth of molten Mg in porous B4C increases with increasing time,and the penetration rate is faster first and then tends to be stable.The infiltration depth can reach more than 2.2 cm after 60 min for Mg,while MgSi alloy,under the same conditions,has a greater depth.The phase composition was tested by XRD.The microstructures of B4C substrates and B4C-MgSi composites were analyzed by scanning electron microscope(SEM).The mechanical properties were also studied.The results show that the porosity of B4C-MgSi composites have many connected pores,and the density is more than 98%after the melting.The composites displays high rockwell hardness(71.3±3.3 HRA),good bending strength(285.81±11.2 MPa)and high fracture toughness(5.27±0.53 MPa·m^1/2).A mixed fracture morphology of B4C-MgSi composite is indicated.It is different from the brittle fracture of B4C substrates.

关 键 词：反应熔渗 熔渗动力学 碳化硼 MG-SI合金 断裂韧性 

分 类 号：TB332[一般工业技术—材料科学与工程]