抄録
Among the whole series of binary alloy-systems which so far have been investigated, there are about thirty cases in which continuous solid solutions are formed. In a survey of all these systems the present writer gives following results.
I. For the formation of continuous solid solution the following factors are to be considered. Firstly, Lattice-Type Factor-as was already suggested by several investigators the two component metals must have the same lattice type. Secondly, Atomic Size Factor which was put forward by Hume-Rothery. Thirdly, Valency and Valency-Electron Factors which were also proposed by Hume-Rothery (including valency electron concentration, electro-negative valency effect and relative valency effect, etc.).
In most cases of the continuous solid solution systems the two component metals generally belong to the same group in the periodic table. This is in accordance with the first and third factors above stated. But, on the other hand, considerable numbers of exceptional cases to this general tendency are known and the writer found that these can be classified as follows. (a) Alloy-systems between IB group elements (Cu, Ag and Au) and VIIIc-group elements (Ni, Pd and Pt). (b) Systems Fe-V and Fe-Cr. In the systems of (a) class the component metals belong to the neighbouring groups in the periodic table, while in (b) class they are situated in the same period in the table. Therefore, the writer believes that the Periodic Position or Atomic Structure Factor must be introduced as the fourth factor for the formation of continuous solid solution.
II. A minimum point on the liquidus curve in a continuous solid solution system seems to occur nearly at such a composition as to which a law of simple integral ratio can be applied. Formerly Stockdale has put forward that the same rule applies to eutectic mixture in binary system. Both of these facts are justified, because the minimum point in continuous solid solution system can be taken as to correspond to the eutectic point in simple eutectiferous system.
