powder productıon and nano materıals - 6th International Powder ...

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6. ULUSLARARASI TOZ METALURJİSİ KONFERANSI ve SERGİSİ
th INTERNATIONAL POWDER METALLURGY CONFERENCE & EXHIBITION
Reinforcement content is an important factor controlling the strength of Al–SiC composites. It is known that for a
given matrix alloy and reinforcement, the yield and ultimate tensile strengths generally increase with increasing
reinforcement content, and a similar increase is expected for the stiffness of the composite [2,3].
Sound velocity measurement results are tabulated in Table 3. Figure 3 shows the variation of longitudinal and
transversal wave velocities with respect to the amount of SiC. The velocity of ultrasonic wave propagating in an
inhomogeneous medium depends upon the overall effective stiffness and density of the medium. The SiC is much
stiffer than the Al matrix while its density is comparable to that of the matrix. When SiC content increases, the stiffness
and the elastic modulus increases. Thus, ultrasonic waves propagate faster in the SiC reinforced Al MMCs
than in those without reinforcement, and the propagation rate of the wave increases with increasing amount of SiC
reinforcement.
Set
AlCu
AlSi
Table 3. Velocities of longitudinal and transversal waves
SiC
(wt.%)
ρtheoretical ρmeasured v (m/sec) L v (m/sec)
T
0 2,78 2,56 3819 2660
10 2,81 2,65 5147 2986
20 2,85 2,80 6788 3566
30 2,89 2,85 7246 3719
0 2,68 2,39 3268 2185
10 2,72 2,40 3770 2858
20 2,77 2,60 6443 3605
30 2,82 2,77 7385 4086
Figure 3. Changes in the velocities of longitudinal and transverse waves with %SiC
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