Improvement of heat resistance of aluminium alloys by addition of zirconium-(3)

Abstract

As the third report of the series of experimental research to improve the heat-resistivity of aluminium alloys by means of addition of a small amount of zirconium, the result obtained from experiments on nine casting alloys listed in Table 1 have been described. Heating test was carried out at 400°C and 500°C respectively up to 100 hours and the softening behavior of the alloys were compared through the measurement of Vickers hardness as seen in Fig. 1, and 2. The effect of zirconium was found to be the most remarkable in No. 1 (Y alloy), No. 2 (hydronarium) and No. 3 (Al-Zn-Mg), all of which, even after the heating of 100 hours at 400°C, can retain the same value as-cast hardness. Slight softening, however, was observed at 500°C when they are heated for 100 hours.The results of the tensile test carried out at room temperature after the heating of 100 hours at 400°C are listed in Table 2 and the hot tensile test data obtained at 400°C are shown in Table 3. The effect of zirconium has been clearly recognized in some casting alloys as in the case of several wrought alloys described in our previous reports.