Abstract
The low-frequency internal friction behavior of SiC particle reinforced Al matrix composites was studied over a temperature range from 23°C to 550°C at frequencies of 0.1, 1 and 5 Hz. The experimental data were analyzed in terms of the K-G-L dislocation theory and the anelastic relaxation of grain boundary sliding. Two internal friction peaks of the composites were respectively observed over the temperature ranges of 100~250°C and 200~500°C. The dislocation motion is the important damping mechanism of the composites at low temperatures, while the grain boundary relaxation plays a dominant role at high temperatures. The activation energies for dislocation relaxation and grain boundary sliding are 1.2 eV and 1.57 eV, respectively.
Highlights
SiC particle reinforced Al matrix composites (SiCp/Al) have great potentials to be used in aircrafts, vehicles, weapons and electronic devices, as high-temperature structural materials because of their enhanced damping capacity, high specific strength and stiffness together with the substantial retention of modulus and strength at elevated temperatures[1,2,3,4]
In order not to omit the details of internal friction, the obtained data in the low temperature ranges are enlarged, and a similar hump is found in each Q-1 vs T curve for the composite
The data of measurements have been obtained over the range of 23 to 550ć at the frequencies of 0.1, 1 and 5 Hz with the strain amplitude kept at the order of 10-5
Summary
SiC particle reinforced Al matrix composites (SiCp/Al) have great potentials to be used in aircrafts, vehicles, weapons and electronic devices, as high-temperature structural materials because of their enhanced damping capacity, high specific strength and stiffness together with the substantial retention of modulus and strength at elevated temperatures[1,2,3,4]. Efforts have been made on measurements of the internal friction in Al matrix composites with discontinuous reinforcements through deformation in a small strain range[5]. The basic elastic behavior of the materials remains to be further investigated especially when the temperature and strain-rate effects on deformation are considered. Such rate dependent elastic behavior is clearly not the ideal elasticity but the anelasticity that can be depicted by a linear differential strain-stress relation, in which an energy dissipative process is involved[6,7]. The absolute value of E* , E12 E22 E * { E , and the ratio E2 E1 tan I represent the absolute elastic modulus and the internal friction, respectively
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