MODIFICATION OF SILUMINS BY NANOCOMPOSITE INTERMETALLIC/OXIDE POWDERS PRODUCED BY MASHS

The process of silumin modifying by introducing nanodispersed powders of intermetalliсs NiAl, FeAl, and composite powders of NiAl / 15% Al₂O₃ and Si / Al₂ O₃ obtained by the method of mechanically activated self-propagating high-temperature synthesis (MASHS) with addition of 10% tungsten or copper to increase the density was studied. It is shown that the developed modifier compositions make it possible to increase mechanical properties of silumin and to obtain improved values as compared with standards. The effectiveness of introduction of nanocomposite MASHS powders is explained by their activity due to destruction of the oxide surface film and creation of nonequilibrium state in the surface region during mechanical activation. With the introduction of all modifiers, in addition to the composite powder NiAl / 15 % Al₂O₃ , ultimate tensile strength of silumin increases. Maximum strength, ductility and hardness are achieved with insertion of MASHS Si/Al₂O₃ powders and addition of tungsten or copper. The introduction of modifiers containing MASHS powders results in changing in distribution, size and amounts of primary and eutectic silicon and improves homogeneity of silumin metal matrix. The use of tungsten and copper improves assimilability of the introduced modifying powders.

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