Corrosion behaviour of aluminium metal matrix composites reinforced with TiC processed by pressureless melt infiltration A. ALBITER 1, *, A. CONTRERAS 1 , M. SALAZAR 1 and J.G. GONZALEZ-RODRIGUEZ 2 1 Tecnologı´a de Materiales, Instituto Mexicano del Petro ´leo, Eje central La ´zaro Ca ´rdenas # 152, San Bartolo Atepehuacan, C. P. 07730, Me´xico D.F, Me´xico 2 UAEM-CIICAP, Av. Universidad 1001, Col. Chamilpa, Cuernavaca, 6225 Morelos, Me´xico (*author for correspondence, e-mail: aalbiter@imp.mx) Received 10 July 2005; accepted in revised form 9 September 2005 Key words: Al-2024 alloy, composites, corrosion, infiltration, TiC Abstract The corrosion resistance of commercial aluminium alloy (2024) and binary Al–Cu x and Al–Mg x alloys reinforced with TiC particles using a pressureless infiltration method has been evaluated in 3.5% NaCl solution using potentiodynamic polarization curves and linear polarization resistance measurements. The TiC preforms were sintered at 1250, 1350 and 1450 °C and infiltrated in the range of 900–1200 °C under argon atmosphere. Some specimens were heat treated at 530 °C for 150 min, water quenched and subsequently artificially aged at 190 °C for 12 h in an argon atmosphere and naturally aged at room temperature for 96 h, respectively. The corrosion resis- tance of the composites was evaluated as a function of the addition of Cu and Mg into the aluminium. In all cases pitting corrosion was observed with or without additions of Cu or Mg, but these elements increased the anodic corrosion current. However, it was found that addition of TiC particles in the composite without heat treatment reduced the anodic current density and the number and size of pits in the Al-2024 alloy. When the heat treatment was applied to the composite, either artificially or naturally aged, the anodic current density of the Al-2024 alloy increased. 1. Introduction Aluminium-alloy based metal matrix composites have the highest priority in applications where a combination of corrosion resistance, low density and high mechanical performance are required, such as in the automotive and aerospace industry. The reinforcement of an aluminium matrix, based on the use of TiC particles is interesting because of its good wettability [1, 2] which results in a clean and strong interface [2–4]. While aluminium alloys are the most common matrix used in metal-ceramic composites, it is reported that the addition of TiC, as reinforcement, improves the mechanical properties at room and high temperatures. In particular, the AlCu-alloy/TiC system provides a favourable combination of electrical and mechanical properties. Comparatively, AlMg-alloy/TiC composites are lighter than AlCu-alloy/TiC. The interface between the matrix and reinforcement plays a crucial role in determining the properties of Metal Matrix Composites (MMCs). Mechanical and physical properties of the MMCs such as strength, stiffness, ductility, toughness, fatigue resistance, creep resistance, thermal expansion coefficient, thermal conductivity and corrosion resistance are dependent on the interfacial behaviour [5]. The main concern is the high corrosion tendency of Al-alloys worsened by the galvanic corrosion between the metallic matrix and more noble fibers or particle reinforcement. Therefore, it is important to study the corrosion behaviour of composites for their application. The corrosion behaviour of composites reinforced with different ceramics, such as Al 2 O 3 , SiC and TiC has been studied by Deuis et al. [6] in 3.5 wt.% sodium chloride solution. They found that the corrosion rate increases in the following order: Al 2 O 3 < SiC <TiC. The corrosion rates of composites were higher than their matrix alloys when they were immersed in NaCl solutions. This has been attributed to localized attack of the MMC at the matrix interface, resulting in pitting or crevice corrosion. The interfaces were preferred sites for passive film breakdown (pitting initiation sites), that produce voids, resulting in an easier breakdown of the oxide layer [7–9]. Pitting in composites has been observed at the reinforcement matrix interface [10–12]. Factors influencing the corrosion of composites include porosity, precipitation of intermetallic phases within the matrix, high dislocation densities at the particle-matrix Journal of Applied Electrochemistry (2006) 36:303–308 Ó Springer 2005 DOI 10.1007/s10800-005-9073-z