Understanding the mechanical behavior of particulate reinforced metal matrix composites.

摘要

Particulate reinforced metal matrix composites (PMMCs) are beginning to make significant contributions in the industries of aerospace, automotive and consumer-related products. Such advances have created an inescapable need for establishing an understanding of the inter-relationship between composite microstructure and mechanical behavior.; In the present study, three kinds of PMMCs were chosen for an assessment of their mechanical performance in view of potential applications in ground transportation, automobile, aerospace and high-performance goods. The aluminum alloys chosen were the precipitation hardened Al-Cu-Mg and Al-Zn-Mg-Cu system because of their promising mechanical properties. The magnesium alloy chosen is based on the binary Mg-6%Zn system. The reinforcement chosen was silicon-carbide (SiC) particulates. To facilitate a better understanding of the mechanical behavior of the composites, the initial microstructure was examined by optical and transmission electron microscopy (TEM). The fatigue and final fracture behavior of aluminum alloy 2009 metal matrix composite and Mg-6%Zn magnesium matrix composite were studied at both ambient temperature (27°C) and elevated temperature of (150°C). The fatigue behavior of 7034 aluminum matrix composite was also examined in the under-aged (UA) and peak-aged (PA) conditions at both ambient (27°C) and elevated temperatures (120°C).; Tensile tests were conducted to determine the basic mechanical properties, and microstructural examination was performed to characterize the initial microstructure of the material. Applying the basic theories governing high and low cycle fatigue behavior of common metals and alloys, the fatigue exponents and constants were determined from the experimental data. Results of the study demonstrate the applicability of traditional fatigue analyses for particulate-reinforced composites.; Also examined, with aid of finite element simulations using ABAQUS software and the periodical unit cell model, was the intrinsic influence of particulate distribution and clustering in dictating the mechanical behavior of discontinuously-reinforced aluminum metal matrix composites. For cyclic fatigue, two types of modeling schemes were evaluated. The fatigue damage evolution model is used to predict the cyclic-stress controlled fatigue response. In the last section the methodology and potential for incorporating the parameters obtained from the experimental study for analyzing the cyclic-plastic strain controlled response is presented.