[On deformation of Au-Pt alloys caused by heat treatment (I) (author's transl)].
We made fifteen kinds of Au-Pt alloy each of which contain 69% gold. We measured the changes of hardness, the deformations of these alloys caused by heat treatment and also the thermal expanison coefficient of these alloys. The results were as follows. 1. The hardness of these alloys as they were cast almost the same as that of those, hardened by heat treatment. 2. The hardest alloy, as cast or hardened by heat treatment, contained 5% platinum, 20% copper and 5% silver. 3. The ability of these alloys to be hardened and softened by heat treatment was strengthened as the amount of platinum decreased and equally as the amount of copper increased. 4. The deformation of these alloys caused by heat treatment decreased as the amount of platinum increased and equally as the amount of copper decreased. 5. The deformation caused by heat treatment of these alloys which were caset by using phosphate-bonded investment was smaller than those of those alloys were cast by using gypsum investment. 6. The thermal expansion (100 degrees C approximately 400 degrees C) of these alloys as cast was larger than that of the alloys which were heated by softening treatment. The thermal-expansion-coefficient and temperature curves of these alloys as they were cast, were at 350 degrees C in the respective maximum point. On the other hand, the thermal-expansion-coefficient and temperature curves of the alloys which were heated by softening treatment, were at 175 degrees C in the respective minimum point.