Using high purity aluminium (99.998%), the equilibrium diagram of the aluminium-zinc system has been re-examined, by means of thermal, differential dilatometric and microscopic analyses as well as a newly devised apparatus. From the results of the experiments, the following conclusions were drawn:-
(1) The liquidus lines of this system have been found in good agreement with the old diagrams.
(2) The solidus lines which were determined by a newly devised apparatus have shown an inflexion point in the range of 58.8% to 80.7% of zinc. (3) An evolution of heat were observed on cooling, in the vicinity of 442°, but it did not accompany sharp peaks. It is probably due to the marked segregation during the process of freezing, because the thermal change is hardly detectable in the heating.
(4) The field of β and β1+β2 were determined by means of thermal and microscopic analyses. The results obtained were found in good agreement with those obtained by the X-ray analysis carried out by Dr. Obinata. (Tetsu to Hagane, 8 (1936), 622.)
A small amount of magnesium has been added to the specimens (>55% of zinc) in order to restrain the β phase from decomposition by quenching.
(5) The eutectic and eutectoid transformation points assigned as were 382° and 283° respectively.
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