Corrosion behaviour of aluminium metal matrix composites reinforced with TiC processed by pressureless melt infiltration

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 resistance 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.