MODIFICATION OF Al-20%Si HYPEREUTECTIC ALLOY STRUCTURE BY COMPRESSION PLASMA FLOW TREATMENT

摘要

The structure of the Al-20%Si hypereutectic alloy surface layer modified by compression plasma flows is investigated. Compression plasma flows are generated in a nitrogen atmosphere by a magnetoplasma compressor of compact geometry. Plasma impact leads to dissolution of intermetallides and primary Si crystals and to the formation of an oversaturated solid solution on the basis of the f.c.c. Al lattice containing Si atoms. The high cooling rate of the melt resulted in structure refinement of the surface layer. An additional modification of the surface layer is carried out by its alloying with Ti atoms under plasma impact. Structural changes provided an increase in the aluminum alloy micro-hardness. Main trends in structure transformation after plasma treatment are discussed.