INFLUENCE OF METALLURGICAL FACTORS AND HEAT-TREATMENT ON MICROSTRUCTURE AND MECHANICAL-PROPERTIES OF ALSI5CU1

The paper presents results of the tests, that concerned influence of m odification solidification rate and heat treatment parameters on mecha nical properties of AlSi5Cu1 casting alloy, which is widely used in ai rcraft and machine-building industries. It has been found, that the mo st advantageous effect on microstructure and mechanical properties (R- m, R-0,R- 2, A(5), HB) of the alloy exerts modification using mixture of sodium, (AlTiB) and Ti, as well as heat treatment, that consists of precipitation hardening (solution treatment at 525 +/- 5 degrees C du ring 18 h, cooling in water at 20 degrees C followed by ageing at 155 +/- 5 degrees C, 5 h and cooling in air).