Corrosion behavior of as-cast, silicon carbide particulate-aluminum alloy metal-matrix composites

Journal Article · Tue Mar 01 04:00:00 EST 1994 · Corrosion (Houston); (United States)

DOI:https://doi.org/10.5006/1.3293509· OSTI ID:5089946

Buarzaiga, M M; Thorpe, S J ^[1]

---

1. Univ. of Toronto, Ontario (Canada). Dept. of Metallurgy and Materials Science

Corrosion characteristics of as-cast, silicon carbide particulate-aluminum (Al) alloy A356 (SiC[sub p]-A356 [UNS A13560]) were examined in chloride (Cl[sup [minus]]) media using optical and scanning electron microscopy, energy dispersive x-ray analysis, cyclic potentiodynamic anodic polarization, and pit propagation rate test methods. Breakdown potential (E[sub b]) increased slightly as the SiC[sub p] volume fraction increased but decreased as Cl[sup [minus]] concentration increased. Severity of attack increased with increasing SiC[sub p] volume fraction and Cl[sup [minus]] concentration. Correlation of pit initiation sites with microstructural features revealed the critical role of second-phase particles in the composite materials and the corresponding unreinforced alloy matrices. At low Cl[sup [minus]] concentrations, FeMg[sub 3]Si[sub 6]Al[sub 8] intermetallic particles were the most susceptible microstructural features in the unreinforced alloy. The particles were light gray and exhibited script and blade-like morphologies. As Cl[sup [minus]] concentration increased, numerous geometrical pits nucleated within the primary Al phase of the unreinforced alloy. Pitting corrosion attack in the composite occurred preferentially at the Al-FeSiAl[sub 5] interface at low Cl[sup [minus]] concentrations. These particles displayed a blade-like morphology. As Cl[sup [minus]] concentration increased, pits initiated at the SiC-Si and SiC-Al interfaces.

• OSTI ID: 5089946
• Journal Information: Corrosion (Houston); (United States), Journal Name: Corrosion (Houston); (United States) Vol. 50:3; ISSN 0010-9312; ISSN CORRAK
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360604* -- Materials-- Corrosion
Erosion
& Degradation
ALLOYS
ALUMINIUM ALLOYS
ALUMINIUM BASE ALLOYS
CARBIDES
CARBON COMPOUNDS
CHEMICAL REACTIONS
CHLORIDES
CHLORINE COMPOUNDS
COMPOSITE MATERIALS
CORROSION
CORROSIVE EFFECTS
HALIDES
HALOGEN COMPOUNDS
INTERMETALLIC COMPOUNDS
MATERIALS
SILICON CARBIDES
SILICON COMPOUNDS