STRUCTURE AND PHASE-COMPOSITION OF HYPEREUTECTIC SILUMINES INTENDED FOR DEFORMATION

Structure and phase composition of hypereutectic silumines containing up to 22% Si, 3.6% Fe, and 3.5% Mn and their structural evolution upon deformation were studied. The most probable phase constituents in the se alloys are: dendrites or plates of the alpha phase (AlFeSiMn or AlM nSi), needles of the beta (AlFeSi) or delta (AlFeSi) phases, the Si pa rticles formed by high-temperature peritectic or eutectic reactions; n eedles of the (AlTiSi) phase, eutectic silicon and the eutectic precip itates of the (AlFeSiMn) phase of hieroglyph shape. The stratified par ticles observed in some alloys are the products of one or several inco mplete peritectic reactions. The regression equations of the effect of composition on the structural parameters of cast alloys are proposed. Formation of the structure favorable to subsequent deformation is pos sible in the alloys containing below 1.5% Mn and below 2.5% Fe. Howeve r, the total content of these elements should not exceed 2.3%.