ON THE EFFECT OF HEAT TREATMENT OF AL ALLOYS CONTAINING Cu, Sn

The present investigation was carried out to acertain the effect of heat treatment on the natural age hardening and temper hardening of Al alloys containing Cu and Sn which had been used for bearing materials.As these test pieces were prepared by addition of the mother alloys (Cu6Sn5Cu3Sn) and Mg to Al, the results obtained from the study of Al-Cu6Sn5, Al-Cu3 Sn, and Al-Cu6 Sn5-Mg systems were as follows:(1) All the alloys of these systems did not show a natural age hardening at room temperature, and the temper hardening was remarkable except the two alloys containing 2%Cu6 Sn5 or Cu3 Sn. But the addition of 1.5%Mg to these two alloys gave an influence upon the temper age hardening. From these results, it was cartain that Cu and Sn were soluble in Al.(2) By heating these natural aged alloys at 220° for a short time, the hardness increased at first and decreased, and then increased. This first hardening seemed to be a temper hardening without a certain precipitate and the second by it.