THE EFFECT OF SR MODIFICATION AND HOLDING TIME ON Si MORPHOLOGY AND MECHANICAL PROPERTIES OF ETIAL 195 ALLOY

Abstract

Hypereutectic Al-Si alloys are typically used in applications where wear resistance is required. The primary factor that determines the wear properties is the morphology of Si in these types of alloys. Pouring temperature is one of the ways to control Si size and shape. On the other hand, bifilm defects that may be present in the liquid can significantly alter the morphology of Si acting as a heterogeneous nucleant. Therefore in this work, castings were made at 800 degrees C with varying holding time and the effects of bifilm on the Si morphology was studied. Bifilm content was measured by Reduced Pressure Test and image analysis was used to characterize Si morphology. In addition, tensile tests were carried out to correlate Si morphology with mechanical properties.