Page 97 - eBook_Proceedings of the International Conference on Digital Manufacturing V2

Fabrication and Characterization of a Low-Cost Piezoelectric using Rochelle
Salt for Energy Harvesting and Sensor Applications

a) b)

Figure 34: EBSD images showing grain structure: black lines mark
grain boundaries over 10 degrees misorientation. (a) no additives,
(b) with 1300 ppm Ti and 210 ppm B (Nafisi, Szpunar, Vali &
Ghomashchi, 2007).

While various grain refinement techniques exist, such as
inoculation, severe plastic deformation, and rapid solidification,
there is limited comparative analysis of their effectiveness in
SSMP. Recent researchers had critically reviewed these methods
to guide future research and industrial application (Tajudin,
Ahmad, Alias, Razak & Alang, 2023; Ji, Wang & Dong, 2022).

Direct Thermal Method (DTM)

DTM is another technique used in SSMP, mostly involved
aluminium-silicon alloys to assess how mould materials affect
microstructure (Figure ). However, its use with Aluminium 7075
is less common, as this high-strength alloy is harder to cast due to
its tight solidification range and tendency to crack (Ahmad, Naher
& Brabazon, 2014).

A study has been done, aims to fill this gap by exploring the
relationship between pouring temperature, holding time, and the
resulting microstructure in Aluminium 7075. The primary goal is
to achieve a spheroidal microstructure, which is beneficial for
SSM processing due to its low shrinkage porosity and high
integrity. The study demonstrated that a lower pouring
temperature of 665°C, combined with an extended holding time
of 60 seconds, resulted in a finer and more uniform spheroidal
microstructure in Aluminium 7075. As illustrated in Figure , the

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