MODIFICATION OF AL-SI EUTECTIC ALLOYS WITH RARE-EARTH ELEMENTS.

A SYSTEMATIC STUDY HAS BEEN MADE OF THE MODIFICATION OF AL-SI ALLOYS WITH ELEVEN INDIVIDUAL RARE-EARTH ELEMENTS AND A MISCHMETAL. THE MODIFIERS WERE ADDED TO THE ALLOYS BY THE METHODS OF RECIPROCAL REACTION AND ELECTROLYSIS OF THE CORRESPONDING BINARY MOLTEN SALTS OF RARE-EARTH CHLORIDES AND KCL. ON THE BASIS OF METALLOGRAPHIC OBSERVATIONS, IT WAS FOUND THAT EU POSSESSES THE GREATEST MODIFICATION ABILITY. THE MODIFICATION ABILITY OF RARE-EARTH ELEMENTS DECREASES RAPIDLY WITHTHE DECREASE OF THEIR ATOMIC RADII. IT IS ASSUMED THAT THE MODIFICATION ABILITY MAY BE THE RESULT OF THE COMBINED INFLUENCE OF THE VALENCE ELECTRON CHARGE NUMBER, THE ATOMIC NUMBER, AND THE ATOMIC RADIUS. IN CHINESE WITH ENGLISH ABSTRACT.