【摘要】 使用定点离子束切割制样(FIB)并根据透射电镜(TEM)表征,分析了板条马氏体钢干摩擦层内部板条马氏体协调塑性变形、演变为纳米层片结构并发生非晶化的全过程。结果表明,高密度位错缠结和缺陷集中是纳米层片结构的典型特征,这种结构产生的界面在高应变驱动下发生非晶化。这些非晶产物,为进一步细化磨屑和形成表面自润滑层提供结构条件。基于上述实验结果并结合摩擦学和材料学理论建立了干摩擦过程中的非晶化形核模型,计算了发生非晶化的热力条件和能量壁垒。结果表明,根据经典形核理论和晶体向非晶转变的吉布斯自由能壁垒计算公式所建立的干摩擦非晶化形核能量模型,可用于计算发生非晶化必需的临界位错密度值。根据对应的计算结果,可控制摩擦条件用干摩擦应变诱导板条马氏体的固态非晶化。更多还原

【Abstract】 The coordinated plastic deformation, nano-lamination and amorphization in the friction-induced layer of lath martensite steel were characterized via transmission electron microscopy(TEM) observation on samples prepared with fixed-point ion beam cutting(FIB). It was found that high-density dislocation and defects concentrated in nano-lamellar structures. The amorphous structures formed at interfaces between nano-lamellar structures in friction-induced layer under high strain. These amorphous products may be beneficial to the further refinement of the wear debris and thereby the formation of a protective layer. According to the above experimental results, an amorphous nucleation model in dry sliding friction process was established based on tribology-and material-theory, and then the thermal conditions and energy barriers for amorphization were calculated. The results show that the amorphous nucleation energy model in dry sliding friction established according to the classical nucleation theory and the Gibbs free energy barrier calculation formula can be used to calculate the necessary critical dislocation density value for amorphization. According to the calculation results, the solid-state amorphization of the lath martensite can be induced by the dry sliding friction strain under the optimal friction condition.更多还原