(1. 上海交通大學 金屬基復合材料國家重點實驗室， 上海 200030;
2. 中國科學院 上海硅酸鹽研究所 高性能陶瓷與超微結構國家重點實驗室，上海 200050)
摘 要: 評述了影響顆粒增強金屬基復合材料塑性和韌性的各種因素，在此基礎上深入研究了顆粒形狀對SiCp/LD2復合材料塑性和斷裂韌性的影響規(guī)律。 采用有限單元法分析不同形狀的SiC顆粒增強的LD2復合材料的微區(qū)力學環(huán)境和整體力學行為， 結果表明顆粒的尖銳化導致基體內(nèi)應變集中和顆粒尖端斷裂的可能性加劇，因而降低材料的塑性； 而在外加載荷的作用下， 由于復合材料基體整體均處于較高的加工硬化狀態(tài)， 因此顆粒形狀對材料斷裂韌性的影響并不明顯。 鈍化處理過的顆粒和普通顆粒增強的SiCp/LD2復合材料的力學性能對比和斷口分析驗證了有限元分析的結果。 對復合材料的宏觀結構進行設計是提高復合材料韌性的一條有效途徑。對以高體積分數(shù)連續(xù)SiCp/LD2復合材料棒作為增強體的LD2宏觀結構韌化復合材料的研究表明， 與同類普通復合材料相比， 以大比率熱擠出的結構設計復合材料斷裂韌性可提高32%， 已接近基體合金的斷裂韌性水平； 而且材料的斷裂功大大提高， 斷裂過程呈現(xiàn)階段性， 完全改變了傳統(tǒng)復合材料的斷裂模式，避免了普通顆粒增強金屬基復合材料突發(fā)災難性失效的缺點。
關鍵字: 顆粒增強金屬基復合材料；塑性；韌性；有限單元法；宏觀結構設計
（1. State Key Laboratory of Metal Matrix Composites, Shanghai Jiaotong University, Shanghai 200030, P.R.China;
2. State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, P.R.China）
Abstract:The factors influencing the ductility and toughness of particle reinforced metal matrix composites were commented. Taking these as a background, the effect of particle shape on the ductility and fracture toughnessof SiCp/LD2 composites was deeply studied. Finite element method was used to analyze the microzone mechanical environment and overall mechanical behavior of LD2 matrix composites reinforced with different shaped SiC particles. The resultsshow that particle pointing can increase the strain concentration in the matrix and the fracture possibility of the particles. Therefore, the tensile ductility of the composite reinforced with pointed particle will be decreased. When anexternal load is applied, the composite is under a condition of high workhardening, so the particle shape has little effect on fracture toughness of the composites. Comparison on the mechanical properties and fracture surface analyses of two SiCp/LD2 composites reinforced with blunted and conventionalparticles validates the results of finite element analyses. Designing the macrostructure of composite is an efficient way to improve toughness. LD2 matrix macrostructuretoughening composites reinforced with continuous high volume fraction SiCpLD2 composite bars were studied. Compared with similar conventional composite, the fracture toughness of the structuredesigned composite extruded by alarge ratio can be increased by 32% and is close to the fracture toughness levelof unreinforced matrix alloys. Furthermore, the fracture energy of this kind ofcomposites is greatly improved. Their fracture occurs by stages. This macrostructuredesigned method changes the fracture model of the conventional composites completely and can avoid the disadvantage of catastrophic failure of conventional particle reinforced metal matrix composites.
Key words: particle reinforced metal matrix composite； ductility； toughness； finite element method； macrostructuredesign
