Particle reinforced metal matrix composites are now being produced commerically, and in this paper the current status of these materials is reviewed. The different types of reinforcement being used, together with the alternative processing methods, are discussed. Depending on the initial processing method, different factors have to be taken into consideration to produce a high quality billet. With powder metallurgy processing, the composition of the matrix and the type of reinforcement are independent of one another. However, in molten metal processing they are intimately linked in terms of the different reactivities which occur between reinforcement and matrix in the molten state. The factors controlling the distribution of reinforcement are also dependent on the initial processing method. Secondary fabrication methods, such as extrusion and rolling, are essential in processing composites produced by powder metallurgy, since they are required to consolidate the composite fully. Other methods, suc...

Particle reinforced aluminium and magnesium matrix composites

https://hal.archives-ouvertes.fr/hal-01282728/document

A numerical method for computing the overall response of nonlinear composites with complex microstructure

Effective properties of composite materials with periodic microstructure : a computational approach

Metal Matrix Composites

In a numerical micromechanical study of void nucleation, a framework is used where constitutive relations are specified independently for the matrix, the void-nucleating particles and the interface. Plane strain analyses are carried out for a doubly periodic array of circular cylindrical particles. The particles are taken to be rigid and the elastic-plastic deformations of the matrix are described in terms of continuum crystalline plasticity, using a planar crystal model that allows for three slip systems. Comparison is made with void-nucleation predictions based on a corresponding flow theory of plasticity with isotropic hardening. The crystal model can give rise to shear localization at the particle-matrix interface and shear localization, which leads to large localized strains in the matrix, is found to inhibit decohesion. The role of the triaxiality of the stress state in determining whether decohesion or localization occurs first is investigated. A parameteric study is also carried out for a crystal matrix using two descriptions of the interface shear behaviour; one is periodic in the shear displacement across the interface, while the other allows for shear decohesion.

https://iopscience.iop.org/article/10.1088/0965-0393/1/2/001/pdf

Void nucleation by inclusion debonding in a crystal matrix

An experimental and numerical study of deformation in metal-ceramic composites

Microstructural development in an aluminum alloy-SiC whisker composite

The precipitation characteristics, the mechanisms of accelerated aging, and the variation of uniaxial tensile stress-strain behavior in response to controlled variations in matrix microstructure were investigated for a 2124 AlSiC whisker composite. The yield strength of the composite was found to be independent of matrix aging condition. However, the overall ductility decreased monotonically with an increase in aging time. A finite element analysis of the constitutive response of the composite is presented. The results of these calculations, as well as the predictions of several models for composite strengthening available in the literature, were compared with the experimental results. The presence of brittle whiskers in aluminum leads to a significant build-up of hydrostatic stresses in the matrix during plastic deformation. Void formation in the matrix of the composite as well as at the whisker-matrix interface appears to play an important role in controlling the overall failure mechanisms. Transmission electron microscopy observations of void formation a whisker ends are described for composite specimens strained in tension at room temperature and at 300°C. A detailed discussion of matrix deformation and interfacial debonding is presented in an attempt to identify the origins of low ductility in discontinuously reinforced metal-ceramic composites.

On microstructural evolution and micromechanical modelling of deformation of a whisker-reinforced metal-matrix composite

Accelerated aging in cast Al alloy-SiC particulate composites

The effects of SiC reinforcement and matrix aging treatment on fatigue crack growth behavior in a powder metallurgy aluminum 2124 alloy-SiC whisker composite were investigated. The microstructures were designed such that the matrix of the composite material and the unreinforced control aluminum alloy 2124 with an identical processing history had similar hardness and precipitation characteristics. The threshold stress intensity factor range ΔK0 for tensile fatigue crack growth was obtained using a procedure whereby mode I precracks were initiated in uniaxial cyclic compression prior to tension fatigue. The composite exhibits a ΔK0 value which is about twice that of the control alloy. However, ΔK0 is relatively insensitive to variations in both the aging treatment and the mean stress of the fatigue cycle in both the composite and the control alloy. Possible mechanisms underlying this trend are discussed.

T. Christman

Papers

An experimental and numerical study of deformation in metal-ceramic composites

Microstructural development in an aluminum alloy-SiC whisker composite

On microstructural evolution and micromechanical modelling of deformation of a whisker-reinforced metal-matrix composite

Accelerated aging in cast Al alloy-SiC particulate composites

Effects of SiC reinforcement and aging treatment on fatigue crack growth in an AlSiC composite