High-cycle fatigue of a metal matrix composite based on an aluminum alloy 7075-T1 reinforced with silicon carbide particles

Abstract

The article presents results of the fatigue strength study of a metal matrix composites based on an aluminum alloy of the 7075-T1 grade, containing 20 vol.% silicon carbide obtained by powder technology using mechanical alloying followed by hot pressing. The high-cycle fatigue (HCF) study was carried out at five levels of stress amplitude at room temperature and at four levels of stress amplitude at high temperature (100°C). Smooth samples of corset type with a circular cross section were manufactured in accordance with the requirements of GOST 25.502–79. Synthesized samples went through the heat treatment stage characteristic of the matrix aluminum alloy 7075. Spherical particles within the range from 5 to 70 μm served as the raw material for the initial matrix of the composite material, and the raw material for the reinforcing component were silicon carbide powder particles, which after a long mechanical alloying with matrix particles take the form of granules from 400 to 600 microns.The study of fatigue characteristics led to the conclusion that the introduction of a 20% reinforcing phase into the 7075-T1 matrix alloy based on silicon carbide particles made it possible to achieve a 1.3 times increase in endurance limits based on 2·107 cycles. An increase in the test temperature (100°C) leads to a decrease of 8% in the endurance limit. The change in the values of progressive deformation and resonance frequency during testing at room and high temperatures (100°C) is considered. At room temperature, it was found that with increasing durability, progressive deformation accumulates. At high temperature (100°C), it was found that with a decrease in durability, resonance frequency decreases more pronouncedly at each stress level.