STRUCTURE AND PROPERTIES AL-SI IN-SITU CO MPOSITE

Relationship between mechanical properties and growth rate of Al-10Si- 0,2Mn-0,2Mg-0,5Fe (wt%) composite was studied. Hypoeutectic alloy was directionally solidified by Bridgman method with temperature gradient in liquid at L/S interface 7 x 10(3) K/m. Growth rate was varied withi n the interval from 2.78 up to 1.25 x 10(3) mum/s, The growth rate inf luences the structure and the mechanical properties of composite. The relations between ultimate tensile strength, yield strength, hardness and growth rate are expressed through the modified Hall-Petch relation . Fracture surfaces revealed ductile fracture of matrix and brittle fr acture of Si-phase.