Numerical Simulation And Experimental Research Of ZA35 Alloy Fabricated By Directional Solidification

Zn-Al Alloy with high strength and hardness, good wear resistance and antifriction properties. Part of Zn-Al alloy has used to make bearing, bearing wear resistant materials to replace the traditional copper alloy by now. However because of the width of the crystalline temperature, the alloy exist serious segregation?low shrinkage defects Under the condition of the conventional casting. Directional solidification technology can obtain excellent columnar crystal or polycrystalline structure, effectively improve the mechanical and physical properties of Zn-Al alloy.Microstructure numerical simulation technology can study the process of solute division, crystal morphology, crystal nucleation and grain growth on the grain size. In this paper, the evolutions of interface morphology and structure are simulated for ZA35 alloy using the CAFE method coupled by macro calculation with micro calculation.To effectively restrain the formation of center equiaxed grain promote the growth of columnar crystal, through increasing pouring temperature, make the solid liquid interface front method of liquid phase in the overheated state. But if the pouring temperature is too high will cause the featheriness solidification microstructure. The effect of applying different heat transfer coefficient to the casting solidification end has been discussed. In this article has also explore the effect of different withdrawal rate under the same thermodynamics of Solidification o directionally solidified microstructure. Simulation results show that:with the increase of heat transfer coefficient, speed up the cooling rate. The cast of chilling area is increased, the middle transition zone area is reduced, can quickly into the plateau. With the increase of draw speed, the secondary dendrite arm spacing decreases,also the middle transition region area will be narrow.The experiment of ZA35 alloy directional solidification was carried out with homemade Bridgman horizontal directional solidification furnace. The results show that secondary dendrite arm spacing decreases with the increase of draw rate, increase of the magnetic induction intensity led to secondary dendrite coarsening. Experimental results are in conformity with the simulation results.