The Mechanical Performance of In Situ Processed …
5
effect of carbon to titanium ratio on the formation and distribution of in situ titanium
carbide precipitates in the nickel matrix.
Nickel exhibits excellent resistance to corrosion and wear, and has high ductility
and toughness, and has a low coefficient of thermal expansion. Nickel and nickelbased superalloys have been widely used in aerospace, automotive, and numerous
other industries due to its attractive properties such as heat resistance, resistant to
fatigue, resistant to oxidation and abrasion, and its ability to maintain its shape and
strength even at high temperature [9, 10]. Titanium carbide possesses an excellent
combination of properties such as high hardness of 3200 (HV), high Young’s modulus
(440 GPa), high melting point (3200 °C), low density (4.93 g/cm
3 ), low coefficient of
friction (CoF), excellent resistance to abrasion, corrosion, and wear. These significant
properties make titanium carbide a suitable candidate as rigid ceramic reinforcement,
adding high mechanical strength to the metal matrix [12–15]. Therefore, titanium
carbide is a prominent reinforcement material for ductile and tough nickel base
metal matrix, adding high mechanical strength to the nickel matrix. It makes an
excellent hybrid material for automotive, petrochemical, aerospace industries, and
high-temperature structural applications where high compressive strength, low CoF,
and high wear resistance are necessary at elevated temperatures. Since nickel has
a minimal affinity towards carbon and does not form an equilibrium carbide phase,
it makes nickel a suitable metal matrix for titanium carbide reinforcement. Also,
in comparison with other ductile metals, nickel leads to an improved interfacial
bonding in titanium carbide reinforced nickel matrix as it exhibits a low wetting angle
with titanium carbide [6]. Hence, the combination of nickel and titanium carbide
was selected for the metal matrix composite due to its remarkable properties and
significant importance in industrial applications. Moreover, by altering the carbon
to titanium ratio in Ni-TiC-C composites, the volume fraction of titanium carbide
precipitates can be altered. Additional graphite can also be engineered within the
microstructure, which results in improved tribological performance. This additional
graphite phase exhibits lower shearing strength under friction; thus, it remarkably
enhances lubrication and reduces CoF, making it a significantly promising material
for surface engineering application [6, 7].
Mechanical alloying is a mechanochemical process by which in situ ceramic reinforcement can be formed in the metal matrix via mechanically activated endothermic
chemical reaction using elemental powder material. Mechanical alloying allows the
production of advanced composite materials, which was difficult or impossible to
fabricate with traditional techniques [16, 17]. Mechanical alloying (MA) is a solidstate processing technique allowing the processing of refined microstructure and
homogeneous dispersion of nanosized in situ reinforcement, which significantly
improves the mechanical properties of the composite [18, 19]. Depending upon
factors such as desired phases, microstructure, and properties factors, the selection,
and optimization of processing parameters such as milling speed, milling duration,
and milling media are necessary [19]. Previously, it is indicated that particle size
has a tremendous influence on the recrystallization process, which in turn affects
the grain size and the resultant microstructure of the sintered composites [20]. Hall–
Petch relationship states that the grain size has a significant influence on the strength
5
effect of carbon to titanium ratio on the formation and distribution of in situ titanium
carbide precipitates in the nickel matrix.
Nickel exhibits excellent resistance to corrosion and wear, and has high ductility
and toughness, and has a low coefficient of thermal expansion. Nickel and nickelbased superalloys have been widely used in aerospace, automotive, and numerous
other industries due to its attractive properties such as heat resistance, resistant to
fatigue, resistant to oxidation and abrasion, and its ability to maintain its shape and
strength even at high temperature [9, 10]. Titanium carbide possesses an excellent
combination of properties such as high hardness of 3200 (HV), high Young’s modulus
(440 GPa), high melting point (3200 °C), low density (4.93 g/cm
3 ), low coefficient of
friction (CoF), excellent resistance to abrasion, corrosion, and wear. These significant
properties make titanium carbide a suitable candidate as rigid ceramic reinforcement,
adding high mechanical strength to the metal matrix [12–15]. Therefore, titanium
carbide is a prominent reinforcement material for ductile and tough nickel base
metal matrix, adding high mechanical strength to the nickel matrix. It makes an
excellent hybrid material for automotive, petrochemical, aerospace industries, and
high-temperature structural applications where high compressive strength, low CoF,
and high wear resistance are necessary at elevated temperatures. Since nickel has
a minimal affinity towards carbon and does not form an equilibrium carbide phase,
it makes nickel a suitable metal matrix for titanium carbide reinforcement. Also,
in comparison with other ductile metals, nickel leads to an improved interfacial
bonding in titanium carbide reinforced nickel matrix as it exhibits a low wetting angle
with titanium carbide [6]. Hence, the combination of nickel and titanium carbide
was selected for the metal matrix composite due to its remarkable properties and
significant importance in industrial applications. Moreover, by altering the carbon
to titanium ratio in Ni-TiC-C composites, the volume fraction of titanium carbide
precipitates can be altered. Additional graphite can also be engineered within the
microstructure, which results in improved tribological performance. This additional
graphite phase exhibits lower shearing strength under friction; thus, it remarkably
enhances lubrication and reduces CoF, making it a significantly promising material
for surface engineering application [6, 7].
Mechanical alloying is a mechanochemical process by which in situ ceramic reinforcement can be formed in the metal matrix via mechanically activated endothermic
chemical reaction using elemental powder material. Mechanical alloying allows the
production of advanced composite materials, which was difficult or impossible to
fabricate with traditional techniques [16, 17]. Mechanical alloying (MA) is a solidstate processing technique allowing the processing of refined microstructure and
homogeneous dispersion of nanosized in situ reinforcement, which significantly
improves the mechanical properties of the composite [18, 19]. Depending upon
factors such as desired phases, microstructure, and properties factors, the selection,
and optimization of processing parameters such as milling speed, milling duration,
and milling media are necessary [19]. Previously, it is indicated that particle size
has a tremendous influence on the recrystallization process, which in turn affects
the grain size and the resultant microstructure of the sintered composites [20]. Hall–
Petch relationship states that the grain size has a significant influence on the strength