超重力场反应加工TiB_2基凝固陶瓷——Ti-6Al-4V多尺度多层次复合研究

Multiscale and Multilevel Composite of Solidified TiB_2 Matrix Ceramic to Ti-6Al-4V Achieved by Reaction Processing in High-gravity Field

采用超重力场反应加工技术,通过陶瓷-钛合金之间熔化连接与原子互扩散,制备出TiB2基凝固陶瓷—Ti-6Al-4V层状复合材料。XRD、FESEM及EDS分析发现,正是作为陶瓷基体相的TiB2片晶(或板晶)可诱发强烈的自增韧机制,使TiC-TiB2细晶凝固陶瓷具有高的弯曲强度与断裂韧性,并且也正是因在超重力场反应加工引发的热真空环境下钛合金与液态陶瓷发生熔化连接与原子互扩散,进而在凝固后期相继诱发TiB2与Ti液的包晶反应、TiB自钛液的析晶反应及TiB与钛液的共晶反应,最终实现以TiB2、TiB尺寸与分布为特征的陶瓷—钛合金多尺度(微米—亚微米—微纳米)多层次(TiC/TiB2—TiC1-x/TiB/TiB2—TiB2/Ti/TiC1-x/TiB—TiB2/TiC1-x/TiB/Ti—TiB/TiC1-x/Ti—TiC1-x/Ti—Ti)复合。

Based on fusion bonding and atomic interdiffusion between the ceramic and Ti alloy, the layered composite of the solidified TiB2 matrix ceramic to Ti-6Al-4V alloy was achieved by reaction processing in high-gravity field. XRD, FESEM and EDS results show it is just the intensive self-toughening mechanism initiated by fine platelets of TiB2 primary phases that the solidified ceramic present a excellent combination of high flexural strength and high fracture toughness; meanwhile, as a result of fusion bonding between the liquid ceramic and Ti alloy in thermal-vacuum circumstances induced by reaction processing in high-gravity field, followed by intensive atomic interdiffusion between the liquid ceramic and liquid titanium, peritectic reaction of the solidified TiB 2 and liquid Ti has to take place at the final stage of material solidification, followed by direct growth of TiB solids from liquid Ti and subsequent eutectic reaction of TiB solids and liquid Ti; finally, the compsoite of the solidifed ceramic with Ti alloy is achieved in multiscale (micrometer/submicrometer/ micro-nanomter) and multilevel (TiC-TiB2 /TiC 1-x-TiB-TiB2 /TiB2 -Ti-TiC 1-x-TiB/TiB2-TiC1-x -TiB-Ti/TiB-TiC 1-x -Ti/TiC 1-x-Ti/Ti) characterized by the size and distribution of TiB2 and TiB phases.