(1. 陜西理工學院 材料科學與工程學院，漢中 723003；2. 陜西科技大學 材料科學與工程學院，西安 710021)
摘 要: 以Ti-Al-TiO2反應體系為基礎，添加不同含量的Nb2O5粉，采用壓力協(xié)助原位合成Al2O3顆粒增強的雙相TiAl基復合材料，對復合材料的組織和力學性能進行了分析討論，并探討了其增韌機制。結果表明：Nb2O5的摻雜使復合材料的相對密度和硬度得到提高，抗彎強度和斷裂韌性在Nb2O5摻雜量為6%(質量分數(shù))時達到最大，分別為398.38 MPa和6.992 MPa·m1/2。微觀組織分析表明，獲得了雙相組織，Al2O3顆粒分布于基體晶界處；隨Nb2O5的摻雜量增大，Al2O3顆粒呈細小彌散分布，同時基體晶粒尺寸也減小。雙相基體晶粒的細化及Al2O3顆粒的彌散分布是賦予材料高韌性的主要增韌機制。
關鍵字: 雙相TiAl合金；Al2O3；原位反應；組織結構；力學性能；增韌機制
（1. Department of Materials Science and Engineering, Shaanxi University of Technology,Hanzhong 723003, China;2. School of Materials Science and Engineering,Shaanxi University of Science and Technology, Xi’an 710021, China ）
Abstract:Abstract: In situ Al2O3 particles reinforced two-phase TiAl-based composites were prepared by pressure-assisted high-temperature reaction sintering of Ti-Al-TiO2-Nb2O5 system. The microstructure and mechanical properties of the composites were investigated. The toughening mechanism was also analysed. The results show that the relative density and Rockwell hardness of the composites increase with increasing Nb2O5 content. When the Nb2O5 content is 6% (mass fraction), there presents a better bending strength and fracture toughness, and the bending strength attains 398.38 MPa, moreover, the fracture toughness reaches 6.992 MPa·m1/2. The analysis of the microstructures reveals that it obtains a submicron α2/γ dual phase structure, and the Al2O3 particles distribute on the grain boundary. The in situ Al2O3 particles are dispersively distributed and the grains are refined with increasing Nb2O5 content. Two-phase TiAl grain refining and Al2O3 particles dispersive distribution are the main toughening mechanisms.
Key words: two-phase TiAl alloy; Al2O3; in situ reaction; microstructure; mechanical property; toughening mechanism
