researchers working on aluminum- and magnesium-based composites reinforced with
nanoparticles [70–72].
SiC particles, added as a microwave susceptor and dispersed in the matrix, will be heated
preferentially by microwaves and may help to improve the interfacial bonding between the
reinforcements and the matrix.
Comparing Tables 4.20 and 4.22, it can be observed that, in general, for all the different
composite formulations studied so far, microwave-sintered magnesium composites display
improved hardness and 0.2 % yield strength over microwave-sintered monolithic magnesium.
This indicates that microwave sintering, in addition to the synthesis of pure metals,
can also be used for the synthesis of different composite materials. Mechanical characterization
in terms of hardness and tensile properties also reveals that the properties of
microwave-sintered magnesium composites are generally superior or comparable with
other magnesium composites that were processed using conventional processing methods,
as shown in Table 4.22.
4.3.5.2 Effect of Microwave Heating Rate on Properties of Pure Magnesium
In an on-going study carried out by the authors, the effect of varying the microwave
heating rate on the properties of pure magnesium is currently being investigated. Based on
preliminary results from the tensile testing of the various samples, as shown in Figure 4.51,
an optimum microwave heating rate of approximately 30 degrees per minute produces the
best overall combination of strength and failure strain for pure magnesium. The strength
and failure strain of pure magnesium improves with increasing the heating rate from 15 to
30 degrees per minute. No significant difference is observed in the strength of pure
magnesium by increasing the heating rate further from 30 degrees per minute to
approximately 48 degrees per minute. However, the failure strain is reduced by approximately
28 %. At the fastest heating rate of 55 degrees per minute, the strength values
decrease while the failure strain exhibits the opposite trend. Further characterization
studies are currently in progress to analyze the trend observed and also to extend the study
to other metals.