Effects of Interfaces on the Off-Axis and Transverse Tensile Properties of Boron-Reinforced Aluminum Alloys.
MIDWEST RESEARCH INST KANSAS CITY MO
Pagination or Media Count:
Tension specimens of boron-reinforced 7075 aluminum and 6061 aluminum were tested at angles of 0, 30 and 90 degrees to the unidirectionally aligned filaments. Metallurgical structures in the matrix and at interfaces were correlated with the stress-strain curves, with acoustic emission from boron-filament breakage during the tests, and with fractographic studies. The effects of aging heat treatments and subzero cooling on tensile properties were related primarily to the changes in metallurgical structures produced in the 7075 aluminum matrix. The filament-matrix interfacial bond strengths exceeded the strength of the matrix alloys. Mildly degraded boron filaments had no apparent effect on the ultimate tensile strength parallel to the filaments but drastically altered the fracture mode in off-axis tensile specimens of 7075 aluminum-boron. In the 0 degree samples, fracture appeared to initiate in the core of boron filaments or at the core-boron interface. Diametral splitting of boron filaments was concluded to occur as a result of the stress state developed in the filaments during their manufacture, and limited the ultimate stengths of off-axis and transverse tension specimens. Author
- Laminates and Composite Materials