Tensile and fatigue properties of a 25 vol% SiC particulate reinforced 6090 Al composite at 300 °C

• Published in: Scripta metallurgica et materialia 1995-03, Vol.32 (5), p.707-712
• Main Authors: Nieh, T.G., Lesuer, D.R., Syn, C.K.
• Format: Article
• Language: English
• Subjects: ALLOYS; ALUMINIUM ALLOYS; ALUMINIUM BASE ALLOYS; Applied sciences; CARBIDES; CARBON COMPOUNDS; COMPOSITE MATERIALS; CRACK PROPAGATION; Cross-disciplinary physics: materials science; rheology; DATA; Exact sciences and technology; EXPERIMENTAL DATA; FATIGUE; Fatigue, corrosion fatigue, embrittlement, cracking, fracture and failure; Fatigue, embrittlement, and fracture; FRACTURE PROPERTIES; INFORMATION; MATERIALS; MATERIALS SCIENCE; MECHANICAL PROPERTIES; Metals. Metallurgy; MICROSTRUCTURE; MORPHOLOGY; NUMERICAL DATA; Physics; SILICON CARBIDES; SILICON COMPOUNDS 360603 > Materials-- Properties; TENSILE PROPERTIES; Treatment of materials and its effects on microstructure and properties
• ISSN: 0956-716X
• DOI: 10.1016/0956-716X(95)91590-L

Discontinuously-reinforced metal matrix composites (MMCs) are attractive for many structural applications because the materials exhibit unusual combinations of structural, physical, and thermal properties. In this paper, the authors present the tensile and fatigue properties of a 25 vol% SiC particulate-reinforced 6090 Al composite at 300 C. Several conclusions can be drawn from this study: (1) The fatigue strength, [sigma][sub e], of 25 vol% SiC[sub p]-reinforced 6090 Al composite decreases from 195 MPa at room temperature to 63 MPa at 300 C. However, the endurance ratio, [sigma][sub e]/UTS, increases from 0.37 at room temperature to 0.50 at 300 C. (2) Fatigue cracks initiate primarily within the matrix or at random sites less than 1 [mu]m in size. However, they occasionally initiate from sites with SiC agglomeration. (3) At 300 C, test samples exhibit large ductility during high-cycle fatigue; deformation strain increases with increasing cycles-to-failure. (4) The macroscopic fatigue fracture mode at 300 C changes from slip band formation at low cycles to intergranular fracture at high cycles. (5) Crack growth occurs through plastic deformation of the matrix without particle fracture or particle/matrix decohesion. (6) The major change in fatigue response of 6090/SiC/25p (T6) with change in temperature from 20 C to 3,000 C appears to be the mechanism of fatigue crack growth. Fatigue crack initiation mechanisms remain largely unchanged.