|
Effect of
Heat Treatment on Corrosion Behavior of AL-4Ti/MgO-SiC
Composites |
|
This
work focuses on the effect of annealing, normalizing and
tempering on corrosion behavior of Al-4Ti/1 wt% MgO-2 wt% SiC
composite fabricated by stir casting method. The XRD analysis
and optical examination indicate that
the heat treatments lead to breaking up the main phase (Al 3 Ti)
in Al-4Ti alloy and form many oxides that cover the composite
surface. Linear and cyclic polarizations have been investigated
in seawater at room temperature by
Potentiostat. The corrosion data showed that the corrosion
potential became more negative for heat treated composites
compared with untreated once. Corrosion current density
decreased after heat treatments. The
normalized composite has lowest corrosion rate due to expose the
specimen to atmosphere for quenching which leads to form SiO 2
in addition to MgO and Al 2 O 3. The breakdown of passive
layer in composite decreased by heat treatments which
assessed by cyclic polarization test. INTRODUCTION o obtain the
best properties of materials, we can manufacture a composite
material which captures a specific
property of each material that is better in the composite.
Appropriate selection of alloy composition and thermo mechanical
processing method give controllable properties of metallic
material. These properties reflect not
only the strength and toughness of materials but also the
relative ease and low cost of fabrication with wide range of
manufacturing processes. The most common composites are metal
matrix composites (MMCs) which are
tailored composites resulting from the addition of
reinforcements to a metal to enhancing specific stiffness
coupled with improved fatigue and wear resistance, or perhaps
increased specific strength combined
with desired thermal properties. Corrosion resistance is the
main obstacles in MMCs. But in aluminum matrix composite, this
problem is reduced due to a protective oxide film which improves
corrosion resistance. The acceleration
in corrosion may originate from electrochemical and chemical
interaction between reinforcements and matrix [1]. There are
many researches discussed the corrosion behavior of aluminum
and its alloys in different media [2-7]. Other researches
focus upon the corrosion behavior of aluminum matrix composites
[8-16]. The current work related to investigate the corrosion
behavior of Al-4Ti/1wt% MgO- wt% SiC
in seawater at room temperature to show the role of MgO and SiC
as reinforcements. Heat treatments include annealing;
normalizing and tempering have been achieved to investigate the
role of these treatments on corrosion
behavior |
|
