Role of Microstructure on the Potential of MAX and MAB Phases …
25
Fig. 3 Digital picture of a Ni-based superalloy foil, and b Cr 2 AlC-Ag composite sample after foil
bearing tests at Honeywell International Facility (Torrance, CA) [56]. (Color figure online)
Interpenetrating MAX Based Composites with 3-3
Connectivity (Type-III Composites)
Figure 1c shows the schematics of 3-3 composites where MAX and metal form
interpenetrating network. In these composites, the metal constitutes 40–60 vol%
of the total matrix. Wang and co-workers [43] also reported superior properties of
Ti 3 AlC 2 and Cu (volume ratio: 60: 40) composites fabricated by mechanical alloying
and liquid phase sintering at 950 °C. These composites showed superior ultimate
compressive strength of (1242 ± 24) MP and low electrical resistance of (0.32 ±
0.01) × 10
−6
m. The authors also proposed that these property enhancements were
due to combinatorial effect of solid solution hardening, grain size, and deformation
of grains by kink bands.
Huang and co-workers [44] reported that hot-pressing 50 vol% Ti 3 AlC 2 and
50 vol% Cu powders at 1150 °C and 30 MPa can lead to the formation of unique
TiC 0.61 and Cu(Al) alloy due to the decomposition of Ti 3 AlC 2 phase. This study
shows that decomposition of MAX phases in metal matrix can be tailored to
design novel composite microstructures in interpenetrating composites. The authors
reported a yield strength and ultimate compressive strength of 770 MPa and 1 GPa,
respectively, in these composites. The authors proposed cross-slip as the deformation
mechanism in these composites. Li and co-workers [45] had formed nanocomposite
coating of 50 weight % Ti 3 AlC 2 -50 weight % Cu by plasma spraying. Due to decomposition of Ti 3 AlC 2 , the authors observed different phases like Cu(Al), and different
Ti-rich oxides like Ti 4 O 5 , TiO 2 , and Al 2 TiO 5 . The resultant coating had a high fracture toughness of 9.4 MPa m
1/2 . This study further supports that in situ precipitated
phases can be effective in shielding crack growth.
Zhang and co-workers [46] showed triboactive behavior due to tribofilm formation
in 50 vol% Al–50 vol% Ti 3 AlC 2 composites which were fabricated by pressureless
sintering in the temperature range of 700–800 °C. Wang and co-workers [47] synthesized Al-matrix reinforced with 40 vol% Ti 2 AlC which formed interpenetrating and
continuous skeleton in the Al-matrix. These composites showed two times higher
25
Fig. 3 Digital picture of a Ni-based superalloy foil, and b Cr 2 AlC-Ag composite sample after foil
bearing tests at Honeywell International Facility (Torrance, CA) [56]. (Color figure online)
Interpenetrating MAX Based Composites with 3-3
Connectivity (Type-III Composites)
Figure 1c shows the schematics of 3-3 composites where MAX and metal form
interpenetrating network. In these composites, the metal constitutes 40–60 vol%
of the total matrix. Wang and co-workers [43] also reported superior properties of
Ti 3 AlC 2 and Cu (volume ratio: 60: 40) composites fabricated by mechanical alloying
and liquid phase sintering at 950 °C. These composites showed superior ultimate
compressive strength of (1242 ± 24) MP and low electrical resistance of (0.32 ±
0.01) × 10
−6
m. The authors also proposed that these property enhancements were
due to combinatorial effect of solid solution hardening, grain size, and deformation
of grains by kink bands.
Huang and co-workers [44] reported that hot-pressing 50 vol% Ti 3 AlC 2 and
50 vol% Cu powders at 1150 °C and 30 MPa can lead to the formation of unique
TiC 0.61 and Cu(Al) alloy due to the decomposition of Ti 3 AlC 2 phase. This study
shows that decomposition of MAX phases in metal matrix can be tailored to
design novel composite microstructures in interpenetrating composites. The authors
reported a yield strength and ultimate compressive strength of 770 MPa and 1 GPa,
respectively, in these composites. The authors proposed cross-slip as the deformation
mechanism in these composites. Li and co-workers [45] had formed nanocomposite
coating of 50 weight % Ti 3 AlC 2 -50 weight % Cu by plasma spraying. Due to decomposition of Ti 3 AlC 2 , the authors observed different phases like Cu(Al), and different
Ti-rich oxides like Ti 4 O 5 , TiO 2 , and Al 2 TiO 5 . The resultant coating had a high fracture toughness of 9.4 MPa m
1/2 . This study further supports that in situ precipitated
phases can be effective in shielding crack growth.
Zhang and co-workers [46] showed triboactive behavior due to tribofilm formation
in 50 vol% Al–50 vol% Ti 3 AlC 2 composites which were fabricated by pressureless
sintering in the temperature range of 700–800 °C. Wang and co-workers [47] synthesized Al-matrix reinforced with 40 vol% Ti 2 AlC which formed interpenetrating and
continuous skeleton in the Al-matrix. These composites showed two times higher