carried out this time on the Ti-Al based composites performed by sintered + forging through the powder metallurgy route by
using different reinforcements such as TiB 2 , TiC, and B 4 C. Quasi static compression and low velocity impact (drop weight)
tests have been performed on the sintered + forging specimens with a drop tower to observe the response of theses composites
under the dynamic loading conditions. Interface and microstructure of these composites have been evaluated by Scanning
Electron Microscope (SEM).
10.2 Experimental Conditions
In the frame of the present work, pure thin sheet scraps, aluminium and Ti-Al (titanium-aluminium) intermetallic sheets were
chosen, for the facility of the joining operation, a pure aluminium foil was also used. All of the specimens were prepared from
different size of scrap sheets by water jet cutting in the Supmeca-Paris, research laboratory. As the reinforcements very fine
AA1050, Boron powders were used to improve mechanical performance of the composites. All of the specimens were first
brushed very rough SiC papers then cleaned with acetone in order to remove any dirty particles at the surfaces before hot
forging process.
All of the sheets were stacked on the top each other in a special steel die then pressed. After that, it has put in the electrical
oven and waited under argon atmosphere up to the hot forging process. After homogenous heating, the composite was forged
at 650–680
C by a hydraulic press at the level of 350 MPa rolled just after being taken out of the furnace. At the second stage
of this process, a post heat treatment was carried out. For this type of the composite, three-point bending (3 PB) tests were
carried out carried out with a Zwick mechanical test system at the strain rate of 1 mm/min. The same idea has been carried out
this time on the composites performed through the powder metallurgy with different reinforcements such as TiB 2 , TiC, and
B 4 C. Quasi static compression low velocity impact (drop weight) tests have accomplished for only sintered specimens
compared by means of carried out with a drop tower. The response of theses composites were evaluated under the dynamic
loading conditions.
10.3 Results and Discussion
10.3.1 Microstructure and Mapping Analyses of the Compositions
Figure 10.1a, b show a typical microstructure of the sandwich sheet specimen Ti-Al based composites reinforced with
AA1050 and Boron. Mapping elementary analyses with together EDS chemical analyse taken on the SEM with back scattered
option (BES). A homogenous a sound microstructure is observed with very fine diffusion due to hot bonding process that hot
forging was performed at 660
C under the inert atmosphere.
10.3.2 Mechanical Behaviour-Superelasticity: 3-Point Bending Test Results
Elasticity behaviour and damage analyses of the Ti-Al sandwich composite sheets have been evaluated by using 3P-Bending
tests under quasi static test conditions. All of the experimental tests was carried out according to the ASTM 790. Standard test
specimens were prepared from hot forged layered composite.
Figure 10.2 indicate schematic presentation of the 3P-Bending test setup installed on the Zwick mechanical test system at
the strain rate of 1 mm/min with microstructure of the sandwich composite of the bended sheet specimen before and after the
plastic deformation. After final damage, certain cracked zone were observed at the centre of the bended specimen (mixture of
AA1050 and Boron) mainly at the pure aluminium side as a soft area around the mixture of the hard boron particles.
At least 4 specimens were tested for the reproducibility of the elasticity behaviour. Spring back behaviour was observed in
regular way on the test specimens after the bending operation. Spring back values are variable between 2% and 5% for two
different composition depending on the reinforcement level as indicated in the former section, depending on the Boron values.
As indicated in the former section, three types of the compositions were prepared for the Ti-Al based composites,
depending on the hard particles added between the layers; Al and Boron. Figure 10.3 show the results of one sandwich
composite without boron and two different sandwich composites containing different percentage of boron, 5 and 10 wt %
respectively.
66
E. Bayraktar et al.
using different reinforcements such as TiB 2 , TiC, and B 4 C. Quasi static compression and low velocity impact (drop weight)
tests have been performed on the sintered + forging specimens with a drop tower to observe the response of theses composites
under the dynamic loading conditions. Interface and microstructure of these composites have been evaluated by Scanning
Electron Microscope (SEM).
10.2 Experimental Conditions
In the frame of the present work, pure thin sheet scraps, aluminium and Ti-Al (titanium-aluminium) intermetallic sheets were
chosen, for the facility of the joining operation, a pure aluminium foil was also used. All of the specimens were prepared from
different size of scrap sheets by water jet cutting in the Supmeca-Paris, research laboratory. As the reinforcements very fine
AA1050, Boron powders were used to improve mechanical performance of the composites. All of the specimens were first
brushed very rough SiC papers then cleaned with acetone in order to remove any dirty particles at the surfaces before hot
forging process.
All of the sheets were stacked on the top each other in a special steel die then pressed. After that, it has put in the electrical
oven and waited under argon atmosphere up to the hot forging process. After homogenous heating, the composite was forged
at 650–680
C by a hydraulic press at the level of 350 MPa rolled just after being taken out of the furnace. At the second stage
of this process, a post heat treatment was carried out. For this type of the composite, three-point bending (3 PB) tests were
carried out carried out with a Zwick mechanical test system at the strain rate of 1 mm/min. The same idea has been carried out
this time on the composites performed through the powder metallurgy with different reinforcements such as TiB 2 , TiC, and
B 4 C. Quasi static compression low velocity impact (drop weight) tests have accomplished for only sintered specimens
compared by means of carried out with a drop tower. The response of theses composites were evaluated under the dynamic
loading conditions.
10.3 Results and Discussion
10.3.1 Microstructure and Mapping Analyses of the Compositions
Figure 10.1a, b show a typical microstructure of the sandwich sheet specimen Ti-Al based composites reinforced with
AA1050 and Boron. Mapping elementary analyses with together EDS chemical analyse taken on the SEM with back scattered
option (BES). A homogenous a sound microstructure is observed with very fine diffusion due to hot bonding process that hot
forging was performed at 660
C under the inert atmosphere.
10.3.2 Mechanical Behaviour-Superelasticity: 3-Point Bending Test Results
Elasticity behaviour and damage analyses of the Ti-Al sandwich composite sheets have been evaluated by using 3P-Bending
tests under quasi static test conditions. All of the experimental tests was carried out according to the ASTM 790. Standard test
specimens were prepared from hot forged layered composite.
Figure 10.2 indicate schematic presentation of the 3P-Bending test setup installed on the Zwick mechanical test system at
the strain rate of 1 mm/min with microstructure of the sandwich composite of the bended sheet specimen before and after the
plastic deformation. After final damage, certain cracked zone were observed at the centre of the bended specimen (mixture of
AA1050 and Boron) mainly at the pure aluminium side as a soft area around the mixture of the hard boron particles.
At least 4 specimens were tested for the reproducibility of the elasticity behaviour. Spring back behaviour was observed in
regular way on the test specimens after the bending operation. Spring back values are variable between 2% and 5% for two
different composition depending on the reinforcement level as indicated in the former section, depending on the Boron values.
As indicated in the former section, three types of the compositions were prepared for the Ti-Al based composites,
depending on the hard particles added between the layers; Al and Boron. Figure 10.3 show the results of one sandwich
composite without boron and two different sandwich composites containing different percentage of boron, 5 and 10 wt %
respectively.
66
E. Bayraktar et al.