Mechanism of Fatigue of Copper at Interfaces

摘要

Studies are made of how torsion fatigue processes in pure copper with free surfaces differ (a) when the copper is covered with an electrodeposited coating (Ni, Cr, Au) and (b) when the copper contains embedded wires of tungsten as in a composite. The aim was to evaluate resulting fatigue performance from microstructural observations. Effects of coatings depend on fatigue amplitude, being in general deleterious at large amplitudes but inherently capable of effecting improvement at small amplitudes, especially if the coating is ductile as gold is. Embedded wires in the composites inevitably accentuated fatigue deformation and cracking of the copper matrix; but could lead to improved performance if used as crack stoppers. Examples of improved performance are given. (Author)