Corrosion characteristics of aluminium based metal matrix composites

Abstract

There is a growing demand both in aerospace as well as commercial markets for lighter weight, higher stiffness and higher thermal stability materials to solve the design engineer's problems of reduced mass, higher access speeds, improved mechanical and thermal stability for today's advanced technologies. Metal matrix composites satisfy the above mentioned properties. However, corrosion is a major concern as the secondary phase formation in the matrix takes place as a result of ceramic particle addition, which threatens their exploitation for such applications. In the current paper, the corrosion characteristics of different aluminium based metal matrix composites of varying volume fractions of SiC (SiC/Al) has been studied systematically. Pitting corrosion studies have been investigated in detail. Scanning electron microscopy (SEM) has been used not only to understand the nature of corrosion but also to identify the location of corrosion in the matrix phase. X-ray diffraction analysis (XRD) has been used to determine the intermetallics formation. EPMA studies have been carried out to determine the distribution of SiC particulates in the matrix as well as the location of intermetallics. Finally, the corrosion mechanism causing the SiC/Al composites to degrade under marine environmental conditions has been presented and the necessity of finding suitable surface coatings to enhance the corrosion resistance of these composites is stressed.

Studies on corrosion behaviour of sintered aluminium based composites in chloride environment

“…This is a major reason why the choice of reinforcement particles remains essential during the fabrication of aluminium matrix composites. Reports have shown that aluminium composites become susceptible to galvanic corrosion due to the difference in the potentials of the aluminium matrix and the respective reinforcements [22][23][24]. The values seen from the Tafel fit of the potentiodynamic polarization curves of the samples are presented in Table 2.…”

Microstructure and Corrosion Performance of Aluminium Matrix Composites Reinforced with Refractory High-Entropy Alloy Particulates

“…A variety of MMCs has been developed with different matrices such as aluminium, copper, and stainless steel. Aluminium matrix composites (AMCs) reinforced with various particulates including Al 2 O 3 [6][7][8][9], SiC [10][11][12][13], TiC [14][15][16], and B 4 C [17][18][19][20] have been studied.…”

“…Several studies on the electrochemical properties of AMCs reinforced with various ceramic reinforcements, including Al 2 O 3 /SiC [21], B 4 C [17], SiC [10,11], and AlN [22], indicate that the composites exhibit decreased corrosion resistance compared to the monolithic alloy. This is attributed to the breakdown of the continuous passive film on matrixreinforcement interface [23], the formation of galvanic couples between Al and reinforcement [17,24], the formation of voids at matrix-reinforcements interfaces [25], interfacial layers around the reinforcement that may promote the galvanic effect [26], and increase in the dislocation density around particles clusters [27].…”

Corrosion and Hardness Behaviour of Al/GO Nanocomposites Processed by the Ultrasonic Gravitational Stir Casting Method

“…Uniform corrosion occurs on the surface of the composite due to the changes in environmental conditions [11], and localised corrosion mostly occurred in the matrix region and interfacial region in composite materials through chemical reactions. Localised corrosions are stress corrosion [21,22], pitting corrosion [23], crevice corrosion, galvanic corrosion [24], and intergranular corrosion [25].…”