The structure,phase composition,and properties of multialloyed silumins after different heat treatments

1.	Microadditions of Y and La to multialloyed type AL4 alloys influence the temperature ranges of passage of individual stages without changing the character of the hardening and aging processes.
2.	A shortened heat treat cycle in the solid state for multialloyed AL4+Sb+Sr+Y alloy including homogenization at 535±5°C for 4–6 h, water hardening, and aging at 175±5°C C for 4 h has been developed.
3.	For AL4+Sb+Sr+La alloy the maximum strength and plastic properties are obtained after heat treatment by homogenization at 520±5°C for 4–6 h, water hardening, and aging at 175±5°C for 4 h.
4.	The heat treat cycles developed for multialloyed silumins provide an increase in their strength, plasticity, and corrosion resistance as the result of increasing the degree of differentiation of the phases and structural constituents and also redistribution of impurities. In addition, the stability of the alloy properties is increased.

Dnepropetrovsk Metallurgical Institute. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 10, pp. 40–42, October, 1991.