COST 507 - Repositório Aberto da Universidade do Porto

for detennining phase boundary and invariant reaction temperatures. Furthermore,
once the sample starts to undergo an invariant reaction, such as a eutectic reaction etc,
the temperature remains constant as heat is being absorbed/evolved until the reaction is
complete, i.e.dT/dt = zero during the reaction. This results in the sample being in a
condition close to equilibrium throughout and minimises non-equilibrium effects such
as supercooling etc. Also, reactions that lie within as few degrees can be studied (see
for example [92Hor]). A schematic diagram of the Smith rig is given in Figure 1.
Gas out <
Top End Cap
Chilled Water
Jacket
Sample Alumina
Thermocouple Sheath
Silica Sample Tube
Furnace
Tube
Silica Guide Tube
Inner Tube
Sample in Alumina Crucible
Heating Element
Furnace Case
Ceramic Wool
approx. 50mm
Gas In
Bottom End
Cap
Furnace
Thermocouple
Figure 1 Schematic Diagram of the Smith thermal analysis rig.
3. Al-Mn-Si measurements (James Robinson)
Smith thermal analysis experiments have been carried out by Robinson and Hayes on
the Al-Mn-Si system, across the 4wt% Si vertical section in the Al-rich corner of the
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