COST 507 - Repositório Aberto da Universidade do Porto

Two sets of experiments using the differential scanning calorimeter (DSC) were
measured in the Cu-Li-Mg system. The first set of experiments for the samples N11 to
N43 (13 samples) was carried out using the apparatus provided by Perkin-Elmer
model 7 Series at the Helsinki University of Technology (HUT). The second set of
experiments for the samples Nil to N40 (11 samples) was measured using the
apparatus provided by Shimatsu-50 at the University of Porto (Porto). The samples
Nil to N43 were studied using sealed aluminium and stainless steel crucibles under
argon (purity 99.99 vol.%) atmosphere. The samples Nl 1 to N43 were studied using
stainless steel crucibles under helium (99.9999 vol.%) atmosphere.
1.2 Assessment
The evaluation of the Cu-Li-Mg system was based on the DSC experiments. The
experimental datafile was created using the onset or peak values from the
temperatures of the phase transformations and the enthalpy values which were
calculated from the surface area of the peaks obtained. The reference states used in the
optimisation for the enthalpy values were Bcc_A2 (Li), Fcc_Al (Cu), Hcp_A3 (Mg).
The estimated experimental errors were ±5 K for the temperatures and ±10 at.% for
the enthalpy measurements. Figure 1 shows the calculated phase diagram with 8 at.%
Li and the decomposition of the τ (Cu32LigMg6o) phase at 702.7 K.
1300
0.2 0.4 0.6 0.8
MOLE FRACTION MG
Figure 1. The assessed Cu-Li-Mg phase diagram with 8 at.% Li.
- 220 -