The late Takesabro Izawa and Yoshikazu Hosoi
The present investigation was carried out to ascertain 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 (Cu6Sn5 Cu3Sn) and Mg to Al, the results obtained from the study of Al-Cu6Sn6, Al-Cu3Sn, and Al-Cu6Sn5-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%Cu6Sn5 or Cu3Sn.
But the addition of 1.5%Mg to these two alloys gave an influence upon the temper age hardening. From these results,it was certain 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 with-out a certain precipitate and the second by it.
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