Effect of mechanical alloying on sinterability and phase evolution in pressure-less sintered TiB_(2)-TiC ceramics  

作　　者：Tian-Yi Hu Mian-Yi Yao Dong-Li Hu Hui Gu Yu-Jin Wang 

机构地区：[1]Materials Genome Institute,School of Materials Science and Engineering,Shanghai University,Shanghai,200444,China [2]Institute for Advanced Ceramics,School of Materials Science and Engineering,Harbin Institute of Technology,150080,China [3]Key Laboratory of Advanced Structure,Function Integrated Materials and Green Manufacturing Technology,Ministry of Industry and Information Technology,Harbin Institute of Technology,Harbin,150001,China

出　　处：《Journal of Materiomics》2019年第4期670-678,共9页无机材料学学报（英文）

基　　金：financially supported by the National Natural Science Foundation of China(Grant Nos.51532006 and 51472060);Science and Technology Commission of Shanghai Municipality(16DZ2260601);the 111 Project(D16002)of the National Foreign Experts Bureau of China.

摘　　要：Phase relation and microstructure evolution in the pressure-less sintered TiB_(2)‒TiC ceramics preceded with mechanical alloying were systematically studied by a combination of SEM analysis.WC debris from milling balls promotes sintering by dissolving into the TiC phase to achieve dense microstructures at 1600℃.Variation of W solution in TiC grains exposes two types of core-rim structures,with no or more W in dark and white cores respectively but with common medium W in both rims.Diminishing whitecores reveal an exchange reaction between WC and TiC via mechanical alloying to form the Ti_(1-z)W_(z)C phase prior to sintering.The dark-cores inherit from the as-milled TiC power to further enable the reprecipitation of rims from a mixed liquid-phase,which facilitated also the anisotropic growth of TiB_(2) grains.The dark-cores grow persistently in the second-step at 2000℃ enabled by this liquid-phase,which coarsens the TiB2 grains too.With more alloyed phase,sintering was insufficient at 1500℃ with only the surface fluidity from the primary powders,and the second-step sintering increased the fluidity in the liquid-phase to fully densify the binary microstructure.Re-distribution of the alloyed W by two-step sintering rationalizes the evolution process of the binary microstructures and leads to better understanding of the mechanical behaviors.

关 键 词：TiB2‒TiC ceramics Mechanical alloying Core‒rim structures Liquid-phase sintering Microstructure‒Property relationship 

分 类 号：TG1[金属学及工艺—金属学]