Microstructural and Mechanical Characterization of Sintered …
415
Table 5 Comparison of
porosity after sintering and
hot press
Test specimen Porosity after sintering Porosity after hot press
%
%
Sample-1
2.848
2.394
Sample-2
5.696
4.272
Sample-3
6.274
4.880
97.1, 94.3, and 93.7% of theoretical density. Addition of titanium diboride particles in sample-2 improves diffusivity of nano-particles which lowers agglomeration.
Addition of reinforcement particles like TiB 2 and Al 2 O 3 particles in sample-3 has
lower agglomeration which increases sintered density and also alumina can flow and
fill up the pores in samples and Al powders rearrange themselves in contact areas.
Then samples were undergone hot press in vacuum condition; then densities of the
billets were measured for sample-1, 2, and 3; they were 98.1%, 95.7%, and 95.1%,
respectively, which shows marginal enhancement in densities (Table 5).
Porosity of samples-1, 2, and 3 were reduced after hot press by 15.94, 25 and
22.2%.
3.3 Mechanical Properties
Table 6 provides summary of hardness, yield strength, tensile strength and elongation.
Yield strength of sample-2 and sample-3 was increased by 15.7 and 33.3% than
aluminum alloy. Tensile strength of samples-2,3 was increased by 21.38 and 30.6%
than alloy. Wu et al. reported that reinforcement increases strength at cost of ductility
which due to collective effect of solid solution, intermetallics and its constitution.
In sample-1, mechanical property is influenced by θ
(Al 2 Cu) precipitates which
bypasses the dislocations in turn determines size and number of precipitates.
TiB 2 nano-particles in sample-2 which inhibit movement of particles at grain
boundary due to Orowan’s mechanism. These grain boundaries in turn prohibit dislocations due to this strength increase at cost of ductility [31]. It is evident from Table 6;
base metal deformation is higher than composite due to reinforcement which results
in load is transferred from matrix to reinforcement.
Table 6 Mechanical properties
Test specimen
Yield strength
Tensile strength
Hardness
Elongation
MPa
MPa
HRB
%
Sample-1
159
173
144
22
Sample-2
184
210
190
12
Sample-3
212
226
204
6.25
415
Table 5 Comparison of
porosity after sintering and
hot press
Test specimen Porosity after sintering Porosity after hot press
%
%
Sample-1
2.848
2.394
Sample-2
5.696
4.272
Sample-3
6.274
4.880
97.1, 94.3, and 93.7% of theoretical density. Addition of titanium diboride particles in sample-2 improves diffusivity of nano-particles which lowers agglomeration.
Addition of reinforcement particles like TiB 2 and Al 2 O 3 particles in sample-3 has
lower agglomeration which increases sintered density and also alumina can flow and
fill up the pores in samples and Al powders rearrange themselves in contact areas.
Then samples were undergone hot press in vacuum condition; then densities of the
billets were measured for sample-1, 2, and 3; they were 98.1%, 95.7%, and 95.1%,
respectively, which shows marginal enhancement in densities (Table 5).
Porosity of samples-1, 2, and 3 were reduced after hot press by 15.94, 25 and
22.2%.
3.3 Mechanical Properties
Table 6 provides summary of hardness, yield strength, tensile strength and elongation.
Yield strength of sample-2 and sample-3 was increased by 15.7 and 33.3% than
aluminum alloy. Tensile strength of samples-2,3 was increased by 21.38 and 30.6%
than alloy. Wu et al. reported that reinforcement increases strength at cost of ductility
which due to collective effect of solid solution, intermetallics and its constitution.
In sample-1, mechanical property is influenced by θ
(Al 2 Cu) precipitates which
bypasses the dislocations in turn determines size and number of precipitates.
TiB 2 nano-particles in sample-2 which inhibit movement of particles at grain
boundary due to Orowan’s mechanism. These grain boundaries in turn prohibit dislocations due to this strength increase at cost of ductility [31]. It is evident from Table 6;
base metal deformation is higher than composite due to reinforcement which results
in load is transferred from matrix to reinforcement.
Table 6 Mechanical properties
Test specimen
Yield strength
Tensile strength
Hardness
Elongation
MPa
MPa
HRB
%
Sample-1
159
173
144
22
Sample-2
184
210
190
12
Sample-3
212
226
204
6.25