Particulate-reinforced metal matrix composites(PRMMCs)are difficult to machine due to the inclusion of hard,brittle reinforcing particles.Existing experimental investigations rarely reveal the complex material removal...Particulate-reinforced metal matrix composites(PRMMCs)are difficult to machine due to the inclusion of hard,brittle reinforcing particles.Existing experimental investigations rarely reveal the complex material removal mechanisms(MRMs)involved in the machining of PRMMCs.This paper develops a three-dimensional(3D)microstructure-based model for investigating the MRM and surface integrity of machined PRMMCs.To accurately mimic the actual microstructure of a PRMMC,polyhedrons were randomly distributed inside the matrix to represent irregular SiC particles.Particle fracture and matrix deformation and failure were taken into account.For the model’s capability comparison,a two-dimensional(2D)analysis was also conducted.Relevant cutting experiments showed that the established 3D model accurately predicted the material removal,chip morphology,machined surface finish,and cutting forces.It was found that the matrix-particle-tool interactions led to particle fractures,mainly in the primary shear and secondary deformation zones along the cutting path and beneath the machined surface.Particle fracture and dilodegment greatly influences the quality of a machined surface.It was also found that although a 2D model can reflect certain material removal features,its ability to predict microstructural variation is limited.展开更多
Soperplastic tensions on an IM SiCp/2024Al composite were conducted. The microstrvcture and fmcture sudece of the composite under the optimum saperplastic deformation condition were examined. The eoperimental results ...Soperplastic tensions on an IM SiCp/2024Al composite were conducted. The microstrvcture and fmcture sudece of the composite under the optimum saperplastic deformation condition were examined. The eoperimental results show that as the increase of strain during superpldstic deformation, grains fundarnentally remained equiaxed structure, and dislocation density increases gradually and its structure changes hem intererossed into nets each other to tangled and cellular structure,and the amount of liquid phase at the intedeces or gruin boundaries increases gradually. Mcrostructure examination revealed that failure took place by damage accumulation of the pmpressive decohesion of the SiC particle-matrix until a critical volume fruction was reached.展开更多
1.0wt.% carbon nanotube （CNT） reinforced 2024Al matrix composite was fabricated by cold isostatic press and subsequent hot extrusion techniques. The mechanical properties of the composite were measured by a tensile ...1.0wt.% carbon nanotube （CNT） reinforced 2024Al matrix composite was fabricated by cold isostatic press and subsequent hot extrusion techniques. The mechanical properties of the composite were measured by a tensile test. Mean-while,the fracture surfaces were examined using field emission scanning electron microscopy. The experimental results show that CNTs are dispersed homogeneously in the composite and that the interfaces of the Al matrix and the CNT bond well. Although the tensile strength and the Young’s modulus of the composite are enhanced markedly,the elongation does not decrease when compared with the matrix material fabricated under the same process. The reasons for the increments may be the extraordinary mechanical properties of CNTs,and the bridging and pulling-out role of CNTs in the Al matrix composite.展开更多
The microstructure,mechanical properties,and the effects of sliding distance and material removal mechanism on two-body abrasive wear behaviour of hypereutectic Al-Si-Si C composite and its matrix alloy were investiga...The microstructure,mechanical properties,and the effects of sliding distance and material removal mechanism on two-body abrasive wear behaviour of hypereutectic Al-Si-Si C composite and its matrix alloy were investigated.The hypereutectic Al-Si-Si C composite was prepared by stir casting route.The hardness,ultimate tensile strength and yield strength of the composite are increased by 17%,38%,and 30%respectively compared with those of the matrix alloy,while the elongation of the composite is decreased by 48%compared with that of the matrix alloy.The wear rate of the materials is increased with increasing the abrasive size and the applied load and does not vary with the sliding distance.The wear surfaces and wear debris of the materials were characterized by high-resolution field emission scanning electron microscopy(HR FESEM)and wear mechanism was analyzed for low and high load regimes.展开更多
文摘Particulate-reinforced metal matrix composites(PRMMCs)are difficult to machine due to the inclusion of hard,brittle reinforcing particles.Existing experimental investigations rarely reveal the complex material removal mechanisms(MRMs)involved in the machining of PRMMCs.This paper develops a three-dimensional(3D)microstructure-based model for investigating the MRM and surface integrity of machined PRMMCs.To accurately mimic the actual microstructure of a PRMMC,polyhedrons were randomly distributed inside the matrix to represent irregular SiC particles.Particle fracture and matrix deformation and failure were taken into account.For the model’s capability comparison,a two-dimensional(2D)analysis was also conducted.Relevant cutting experiments showed that the established 3D model accurately predicted the material removal,chip morphology,machined surface finish,and cutting forces.It was found that the matrix-particle-tool interactions led to particle fractures,mainly in the primary shear and secondary deformation zones along the cutting path and beneath the machined surface.Particle fracture and dilodegment greatly influences the quality of a machined surface.It was also found that although a 2D model can reflect certain material removal features,its ability to predict microstructural variation is limited.
文摘Soperplastic tensions on an IM SiCp/2024Al composite were conducted. The microstrvcture and fmcture sudece of the composite under the optimum saperplastic deformation condition were examined. The eoperimental results show that as the increase of strain during superpldstic deformation, grains fundarnentally remained equiaxed structure, and dislocation density increases gradually and its structure changes hem intererossed into nets each other to tangled and cellular structure,and the amount of liquid phase at the intedeces or gruin boundaries increases gradually. Mcrostructure examination revealed that failure took place by damage accumulation of the pmpressive decohesion of the SiC particle-matrix until a critical volume fruction was reached.
文摘1.0wt.% carbon nanotube （CNT） reinforced 2024Al matrix composite was fabricated by cold isostatic press and subsequent hot extrusion techniques. The mechanical properties of the composite were measured by a tensile test. Mean-while,the fracture surfaces were examined using field emission scanning electron microscopy. The experimental results show that CNTs are dispersed homogeneously in the composite and that the interfaces of the Al matrix and the CNT bond well. Although the tensile strength and the Young’s modulus of the composite are enhanced markedly,the elongation does not decrease when compared with the matrix material fabricated under the same process. The reasons for the increments may be the extraordinary mechanical properties of CNTs,and the bridging and pulling-out role of CNTs in the Al matrix composite.
基金the financial support received to the first author as a scholarship from MHRD,Government of India.
文摘The microstructure,mechanical properties,and the effects of sliding distance and material removal mechanism on two-body abrasive wear behaviour of hypereutectic Al-Si-Si C composite and its matrix alloy were investigated.The hypereutectic Al-Si-Si C composite was prepared by stir casting route.The hardness,ultimate tensile strength and yield strength of the composite are increased by 17%,38%,and 30%respectively compared with those of the matrix alloy,while the elongation of the composite is decreased by 48%compared with that of the matrix alloy.The wear rate of the materials is increased with increasing the abrasive size and the applied load and does not vary with the sliding distance.The wear surfaces and wear debris of the materials were characterized by high-resolution field emission scanning electron microscopy(HR FESEM)and wear mechanism was analyzed for low and high load regimes.
