Study on the micro-cutting mechanism and tool wear mechanism of aluminum matrix composites reinforced with FeCoNiCrAl high entropy/medium entropy alloy fibers

Abstract

This study aims to explore the micro-cutting mechanisms of 7050 aluminum matrix composites reinforced with FeCoNiCrAl high-entropy alloy (HEA) and medium-entropy alloy (MEA) fibers. The finite element method (FEM) is employed to model the fibers as cylindrical structures, evenly distributed within the matrix. Using custom subroutines, various mechanical parameters, material failure criteria, and evolution laws are set for the fiber phase. Orthogonal cutting simulations are conducted at four typical angles (0°, 45°, 90°, and 135°) to examine the impact of fiber orientation and material composition on cutting forces, tool wear, stress-strain behavior, and sub-surface damage under varying cutting conditions. The results reveal that as the fiber angle increases, the cutting force initially rises before decreasing. The presence of Co and Cr in the fibers leads to higher cutting forces, with Cr showing a more pronounced effect. Cutting depth is positively correlated with cutting force, and at a depth of 45 μm, the influence of fibers on cutting force becomes negligible. When machining HEA/MEA fiber-reinforced composites, tool wear is primarily concentrated at the cutting edge, with CoFeNi fibers causing the most significant wear. The closer the fiber orientation is to the tool's direction of movement, the lower the stress-strain on the tool's front face, which reduces tool wear. Except for the FeCoCrNiAl fibers, all other fibers experience bending failure, with fiber failure occurring mainly at the onset of tool-workpiece contact. Fibers containing Cr exhibit marked brittle failure during cutting, while Co-containing fibers only experience bending deformation, with the 7050Al matrix collapsing. FeCoCrNiAl fibers show the least sub-surface damage, maintaining high fiber integrity, with compression stress propagating widely and tensile stress concentrated mainly at the tool-fiber interface. Conversely, CrFeNi fibers result in the largest sub-surface damage range and a greater area of tensile stress concentration, with almost all fibers damaged. Increasing the fiber angle leads to an expansion of sub-surface damage and a higher degree of fracture, with fibers at 135° showing the highest tensile stress concentration, mainly near the cutting surface.