Pengaruh Kecepatan Pendinginan pada Struktur Mikro dan Kekerasan Paduan Ag-Sn

Abstract

Amalgam alloy consist mainly of ɣ (Ag3Sn) and small amount of δ (Cu3Sn) phases. The microstructure and hardness of these phases are important and these two parameters wil determine the mechanical behaviour of the amalgam. The microstructure and hardness are influenced by the composition of the alloy and the cooling rate at the time of solidification. Three Silver-Tin alloys with the composition of Ag-26,85% Sn are produced by casting technique, and then the alloys were subjected to three different cooling rate condition ie : cooling in the air (as cast), air blown and quenched in the water. X-ray diffraction analysis of three alloys indicated the existence of ɣ (Ag3Sn) phase.The finest microstructure was produced by as cast cooling rate technique. The hardness of these alloys were measured by using of Vickers' Hardness Tester. The result shows that the hardness of as cast alloy is higher than the hardness of air blown and water quenched alloys. In conclusion, the slower the cooling rate at the time of solidification of the alloy produce amalgam alloy having fine microstructure and hardness.