Investigation of the microstructure and physical properties of directionally solidified ternary Al–8.8La–1.2Ni alloy

Abstract

This paper systematically studies the microstructure evolution, microhardness and tensile property of Al–8.8La–1.2Ni ternary alloy with directionally solidified under a wide range of solidification rates by Bridgman-type growth apparatus. The directionally solidified microstructure of studied alloy consists aligned dendrites, and eutectics in the region between them. Primary dendrite arm spacing (λ1), secondary dendrite arm spacing (λ2) and microhardness (HV) were measured from both transverse and longitudinal sections of many samples. Also, ultimate tensile strength (σuts), tensile yield strength (σtys), ultimate compressive strength (σucs) and compressive yield strength (σcys) of the solidified many samples at room temperature the dependence of solidification rate (V) were carried out. The present results show that the solidification rate can change both microstructure and mechanical properties effectively. According to these results, it has been found that, for increasing values of V, the values of λ1 and λ2 decrease, the values of HV, σuts, σtys and σcys increase. Relationships between microstructural parameters (λ1, λ2) and mechanical properties (HV, σuts, σtys and σcys) expressed as function of solidification rate using a linear regression analysis method.