Micromechanics and Effective Elastoplastic Behavior of Two-Phase Metal Matrix Composites

1994 ◽  
Vol 116 (3) ◽  
pp. 310-318 ◽  
Author(s):  
J. W. Ju ◽  
Tsung-Muh Chen

A micromechanical framework is presented to predict effective (overall) elasto-(visco-)plastic behavior of two-phase particle-reinforced metal matrix composites (PRMMC). In particular, the inclusion phase (particle) is assumed to be elastic and the matrix material is elasto-(visco-)plastic. Emanating from Ju and Chen’s (1994a,b) work on effective elastic properties of composites containing many randomly dispersed inhomogeneities, effective elastoplastic deformations and responses of PRMMC are estimated by means of the “effective yield criterion” derived micromechanically by considering effects due to elastic particles embedded in the elastoplastic matrix. The matrix material is elastic or plastic, depending on local stress and deformation, and obeys general plastic flow rule and hardening law. Arbitrary (general) loadings and unloadings are permitted in our framework through the elastic predictor-plastic corrector two-step operator splitting methodology. The proposed combined micromechanical and computational approach allows us to estimate overall elastoplastic responses of PRMMCs by accounting for the microstructural information (such as the spatial distribution and micro-geometry of particles), elastic properties of constituent phases, and the plastic behavior of the matrix-only materials. Comparison between our theoretical predictions and experimental data on uniaxial elastoplastic tests for PRMMCs is also presented to illustrate the capability of the proposed framework. A straightforward extension to accommodate viscoplastic matrix material is also presented to further enhance the applicability of the proposed method.

2019 ◽  
Vol 53 (28-30) ◽  
pp. 4411-4426
Author(s):  
Roberta Cristina Silva Moreira ◽  
Oksana Kovalenko ◽  
Daniel Souza ◽  
Ruham Pablo Reis

In the search for high-performance parts and structures, especially for the aviation and aerospace industry, metal matrix composites appear with prominence. However, despite exhibiting high levels of mechanical properties and low densities, these materials are still very expensive, mainly due to complex production. Thus, this work aims to present and evaluate a novel way of manufacturing metal matrix composites, with relative low cost and complexity: by using low-energy fusion welding to deposit the matrix material on top of continuous metal wire reinforcement. For proof of concept, Al alloy was used as matrix material, a single Ti alloy wire as reinforcement, and gas metal arc welding CMT-Pulse® as the process for material deposition. The simplified Al–Ti composite was evaluated in terms of impact resistance and tensile strength and stiffness. Overall, the mechanical performance of the composite was around 23% higher than that of the matrix material itself (Al), this with only about 2% of reinforcement volume and just over 3% of increase in weight. Analyses of the Al–Ti composite fractures and cross-sections and of chemical composition and hardness of the matrix–reinforcement transition interface indicated the preservation (no melting) of the Ti wire and the existence of a fine contour of bonding between matrix and reinforcement. At the end, a brief discussion on the dynamics of the wire reinforcement preservation is carried out based on high-speed filming.


2015 ◽  
Vol 813-814 ◽  
pp. 195-202 ◽  
Author(s):  
T. Lokesh ◽  
U.S. Mallikarjun

Abstract. In recent years, Aluminium alloy based metal matrix composites (MMC) are gaining wide spread acceptance in several aerospace and automobile applications. These composites possess excellent wear resistance in addition to other superior mechanical properties such as strength, modulus and hardness when compared with conventional alloys. The hybrid composites are new generation of composites containing more than one type, shape or sizes of reinforcements giving superior combined properties of reinforcements and the matrix. In the present work, Al6061 has been used as matrix material and the reinforcing materials selected were SiC and Graphite particulates of 10 to 30µm size. Composites Al6061-Gr (2- 8 wt. %), Al6061-SiC (2 -10wt. %) and Hybrid composites with Al6061 matrix alloy containing 3wt% graphite and varying composition of 2-10wt% SiCp were prepared by stir casting technique. The cast matrix alloy and its composites have been subjected to solutionizing treatment at a temperature of 530 ± 20C for 6 hours, followed by ageing at a temperature of 175 ± 20C for 6 hours. The mechanical properties of as cast and T6 heat treated composites have been evaluated as per ASTM standards and compared. Addition of Graphite particulates into the Al6061 matrix improved the strength and ductility of the composites. Significant improvement in tensile strength and hardness was noticed as the wt. % of SiCp increases in Al6061-SiC composites. Addition of Graphite into Al6061-SiC further improved the strength and ductility of hybrid composites. The heat treatment process had the profound effect in improving the mechanical properties of the studied composites. The microstructural studies revealed the uniform distribution of SiC and Gr particles in the matrix system.


Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2143
Author(s):  
Shaimaa I. Gad ◽  
Mohamed A. Attia ◽  
Mohamed A. Hassan ◽  
Ahmed G. El-Shafei

In this paper, an integrated numerical model is proposed to investigate the effects of particulate size and volume fraction on the deformation, damage, and failure behaviors of particulate-reinforced metal matrix composites (PRMMCs). In the framework of a random microstructure-based finite element modelling, the plastic deformation and ductile cracking of the matrix are, respectively, modelled using Johnson–Cook constitutive relation and Johnson–Cook ductile fracture model. The matrix-particle interface decohesion is simulated by employing the surface-based-cohesive zone method, while the particulate fracture is manipulated by the elastic–brittle cracking model, in which the damage evolution criterion depends on the fracture energy cracking criterion. A 2D nonlinear finite element model was developed using ABAQUS/Explicit commercial program for modelling and analyzing damage mechanisms of silicon carbide reinforced aluminum matrix composites. The predicted results have shown a good agreement with the experimental data in the forms of true stress–strain curves and failure shape. Unlike the existing models, the influence of the volume fraction and size of SiC particles on the deformation, damage mechanism, failure consequences, and stress–strain curve of A359/SiC particulate composites is investigated accounting for the different possible modes of failure simultaneously.


Metals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1400
Author(s):  
Peter Baumli

The paper reviews the preparation of the different metallic nanocomposites. In the preparation of composites, especially in the case of nanocomposites, interfacial phenomena play an important role. This review summarizes the literature on various interfacial phenomena, such as wettability and reactivity in the case of casting techniques and colloidal behavior in the case of electrochemical and electroless methods. The main contribution of this work lies in the evaluation of collected interfacial phenomena and difficulties in the production of metal matrix composites, for both nano-sized and micro-sized reinforcements. This study can guide the composite maker in choosing the best criteria for producing metal matrix composites, which means a real interface with good adhesion between the matrix and the reinforcement. This criterion results in desirable mechanical and physical properties and homogenous dispersion of the reinforcement in the matrix.


Author(s):  
Partha Rangaswamy ◽  
N. Jayaraman

Abstract In metal matrix composites residual stresses developing during the cool-down process after consolidation due to mismatch in thermal expansion coefficients between the ceramic fibers and metal matrix have been predicted using finite element analysis. Conventionally, unit cell models consisting of a quarter fiber surrounded by the matrix material have been developed for analyzing this problem. Such models have successfully predicted the stresses at the fiber-matrix interface. However, experimental work to measure residual stresses have always been on surfaces far away from the interface region. In this paper, models based on the conventional unit cell (one quarter fiber), one fiber, two fibers have been analyzed. In addition, using the element birth/death options available in the FEM code, the surface layer removal process that is conventionally used in the residual stress measuring technique has been simulated in the model. Such layer removal technique allows us to determine the average surface residual stress after each layer is removed and a direct comparison with experimental results are therefore possible. The predictions are compared with experimental results of an eight-ply unidirectional composite with Ti-24Al-11 Nb as matrix material reinforced with SCS-6 fibers.


1989 ◽  
Vol 111 (1) ◽  
pp. 99-105 ◽  
Author(s):  
Z. G. Zhu ◽  
G. J. Weng

A multiaxial theory of creep deformation for particle-strengthened metal-matrix composites is derived. This derivation is based on the observation that there are two major sources of creep resistance in such a system. The first, or metallurgical effect, arises from the increased difficulty of dislocation motion in the presence of particles and is accounted for by a size- and concentration dependent constitutive equation for the matrix. The second, or mechanics effect, is due to the continuous transfer of stress from the ductile matrix to the hard particles and the corresponding stress redistribution is also incorporated in the derivation. Both power-law creep and exponential creep in the matrix, each involving the transient as well as the steady state, are considered. The constitutive equations thus derived can provide the development of creep strain of the composite under a combined stress. The multiaxial theory is also simplified to a uniaxial one, whose explicit stress-creep strain-time relations at a given concentration of particles are also given by a first- and second-order approximation. The uniaxial theory is used to predict the creep deformation of an oxide-strengthened cobalt, and the results are in reasonably good agreement with the experiment. Finally, it is demonstrated that a simple metallurgical approach without considering the stress redistribution between the two constituent phases, or a simple mechanics approach without using a modified constitutive equation for the metal matrix, may each underestimate the creep resistance of the composite, and, therefore, it is important that both factors be considered in the formulation of such a theory.


2021 ◽  
Vol 19 (2) ◽  
pp. 241
Author(s):  
Ruslan Balokhonov ◽  
Varvara Romanova ◽  
Eugen Schwab ◽  
Aleksandr Zemlianov ◽  
Eugene Evtushenko

A technique for computer simulation of three-dimensional structures of materials with reinforcing particles of complex irregular shapes observed in the experiments is proposed, which assumes scale invariance of the natural mechanical fragmentation. Two-phase structures of metal-matrix composites and coatings of different spatial scales are created, with the particles randomly distributed over the matrix and coating computational domains. Using the titanium carbide reinforcing particle embedded into the aluminum as an example, plastic strain localization and residual stress formation along the matrix-particle interface are numerically investigated during cooling followed by compression or tension of the composite. A detailed analysis is performed to evaluate the residual stress concentration in local regions of bulk tension formed under all-round and uniaxial compression of the composite due to the concave and convex interfacial asperities.


2000 ◽  
Vol 6 (5) ◽  
pp. 452-462 ◽  
Author(s):  
Julie M. Cairney ◽  
Robert D. Smith ◽  
Paul R. Munroe

AbstractTransmission electron microscope samples of two types of metal matrix composites were prepared using both traditional thinning methods and the more novel focused ion beam miller. Electropolishing methods were able to produce, very rapidly, thin foils where the matrix was electron transparent, but the ceramic reinforcement particles remained unthinned. Thus, it was not possible in these foils to study either the matrix-reinforcement interface or the microstructure of the reinforcement particles themselves. In contrast, both phases in the composites prepared using the focused ion beam miller thinned uniformly. The interfaces in these materials were clearly visible and the ceramic reinforcement was electron transparent. However, microstructural artifacts associated with ion beam damage were also observed. The extent of these artifacts and methods of minimizing their effect were dependent on both the materials and the milling conditions used.


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