Abstract
In this report, a research has been made concerning the change of the hardness and the crystal growth of Se in accordance with the time of heat treatments by means of the Marten’s scratch hardness tester and of the X-ray method, respectively. And we measured the surface tension in the melting state at each temperatures with the dropping method.
As was shown in Fig. 1, the Marten’s hardness diminished rapidly in 5 minutes, and then after 20 minutes, it began to increase until 4 hours had elapsed. This tendncy was almost opposite to that of the impact value.
By the X-ray method, we found that, in the first stage of the treatment, the crystal had some preferred orientation (see Fig. 2-a), and the internal strain (Fig. 3-a). And then in the second stage the strain disappeared (Fig. 3-b), the crystals showing a random orientation and a grain growth (Fig. 2-b) as well.
When the Debye-Scherrer’s method was applied in the first stage of the treatment, the lattice constant of a-axis expanded and that of c-axis contracted as compared with those in the normal state (see Table 1).
When we measured the surface tension,it satisfied the Eötvos empirical relation up to 300°, while it decreased rapidly around 320° and then gradually diminished (Fig. 5).
