碳化硅增韧氧化铝基陶瓷刀具切削Inconel718合金的刀具界面行为研究

Study on Tool Interface Behavior of Silicon Carbide Toughened Alumina-based Ceramic Tools in Cutting Inconel718 Alloy

通过宏观实验发现在切削过程中刀具的Al_(2)O_(3)/SiC界面发生了断裂;建立了碳化硅增韧氧化铝基陶瓷刀具切削Inconel718镍基合金的分子动力学模型和单一界面的Al_(2)O_(3)/SiC三维界面模型,从原子尺度分析碳化硅增韧氧化铝切削过程的界面行为。在原有势函数的基础上计算了刀具与工件原子间、刀具内部基体与增韧间的Morse势函数,分别计算了单相Al_(2)O_(3)、单相SiC、复相Al_(2)O_(3)/SiC单一界面的界面结合能。研究结果表明:与单相界面相比,复相Al_(2)O_(3)/SiC界面结合强度较高,SiC增韧能够增强刀具的韧性和强度,但切削过程中出现了工件原子扩散到刀具中的现象。对扩散后刀具基体和增韧间形成界面的界面结合能进行了计算,发现刀具的界面结合强度有所降低,使刀具在Al_(2)O_(3)/SiC界面处发生断裂。

Through macro experiments,it was found that during the cutting processes,the Al_(2)O_(3)/SiC interface of the tool breaks,and the macro mechanical properties of the material depended on the microstructure.Therefore,the molecular dynamics model for the cutting of Inconel718 nickel-based alloy with ceramic tool toughened alumina based on silicon carbide and the three-dimensional interface model of Al_(2)O_(3)/SiC were established to analyze the interface behaviors of the cutting processes of toughened alumina based on silicon carbide from the atomic scale.Based on the original potential function,the Morse potential function between the tool and the workpiece atoms,as well as between the matrix and toughening inside the tool was calculated,and the interface binding energy of single-phase Al_(2)O_(3),single-phase SiC and complex phase Al_(2)O_(3)/SiC single interface was calculated respectively.Results show that compared with single phase interface,the complex phase Al_(2)O_(3)/SiC interface bonding strength is higher,SiC toughening can enhance the toughness and strength of the tools.However,during the cutting processes,the workpiece atom diffuses into the tool,and the interface bonding energy between the tool matrix and the toughened interface is calculated.It is found that the diffusion reduces the interface bonding strength of the tools and makes the tool fracture at the interfaces of Al_(2)O_(3)/SiC.