Corrosion characteristics of Al‐Si‐Mg/SiC_p composites with varying Si/Mg molar ratio in neutral chloride solutions

Abstract

The corrosion resistance of Al-Mg-Si/SiC p composites produced by the pressureless infiltration method [using SiC p preforms with 50% porosity containing rice hull ash (RHA) and four custom-made alloys with varying Si/Mg molar ratio] was evaluated in neutral 0.1 M NaCl solutions. The deleterious phase Al 4 C 3 was successfully suppressed in composites with Si/Mg molar ratios of 0.89 and 1.05, but not in those with lower Si/Mg molar ratios (0.12 and 0.49). Results of cyclic polarizations in deareated 0.1 M NaCl solutions showed that with increasing Si/Mg molar ratio, passive current density increased but pitting susceptibility decreased both for reinforced and unreinforced alloys. Immersion tests in aerated 0.1 M NaCl showed that for composites with Si/Mg molar ratios of 0.12 and 0.49 chemical degradation by hydrolysis of Al 4 C 3 was followed by intense anodic dissolution at the matrix-reinforcement interface, while composites corresponding to Si/Mg molar ratios of 0.89 and 1.05 did not exhibit intense localized attack. Possible reasons for the improvement in resistance to localized corrosion are discussed.

Corrosion behaviour of friction stir processed Al–Mg2Si composites

“…Also, the electrolyte temperature was kept at 25°C since most industrial applications of Al-Mg 2 Si composite occur at ambient temperature. Further, most previous studies on the corrosion behaviour of Al-Mg 2 Si composite used this temperature and solution; thus this investigation could be comparable to them [9,10]. Then, the weight loss was measured according to the ASTM G31 standard.…”

“…Although corrosion behaviour is another critical property of the Al–Mg 2 Si composites, in addition to mechanical properties, previous studies have not adequately addressed it. Escalera-Lozano et al [9] investigated the electrochemical and coupling behaviours of Al–Mg–Si alloys containing Mg 2 Si and Si particles. They reported that Si and Mg 2 Si particles acted as cathode and anode, respectively, in the first stages of the corrosion period, which resulted in the selective dissolution of Mg in Mg 2 Si particles.…”

Recent Trends in Processing and Degradation of Aluminium Alloys

“…al., 1997). In another recent investigation, the author´s group focused on the role of Al 4 C 3 in the corrosion characteristics of Al-Si-Mg/SiCp composites with varying Si/Mg molar ratio in neutral chloride solutions (Escalera-Lozano et. al, 2009).…”

Corrosion behavior of mechanically alloyed A6005 aluminum alloy composite reinforced with TiB2 nanoparticles

“…This combination of high specific properties makes AMCs interesting for structural elements in the transport industry . Moreover, ceramic particles commonly employed as reinforcement such as silicon carbide (SiC) or titanium diboride (TiB 2 ) present high strength, stiffness, and excellent fatigue and wear resistance . These mechanical properties can also be improved by a decrease of reinforcement size, from micrometric to nanometric size .…”