Abstract
Aluminium alloys form many important structural components, and the addition of alloying elements contributes to the improvement of properties and characteristics. The objective of this work is to study the influence of thermal variables on the microstructure, present phases, microhardness, dynamic modulus of elasticity, and damping frequency in unidirectional solidification experiments, which were performed in situ during the manufacturing of Al–0.8 Nb and Al–1.2 Nb (wt.%) alloys. Experimental laws for the primary (λ1) and secondary (λ2) dendritic spacings for each alloy were given as a function of thermal variables. For Al–0.8%wt Nb, λ1 = 600.1( T ˙ )−1.85 and λ2 = 186.1(VL)−3.62; and for Al–1.2%wt Nb, λ1 = 133.6( T ˙ )−1.85 and λ2 = 55.6(VL)−3.62. Moreover, experimental growth laws that correlate the dendritic spacings are proposed. An increase in dendritic spacing influences the solidification kinetics observed, indicating that metal/mold interface distance or an increase in Nb content lowers the liquidus isotherm velocity (VL) and the cooling rate (Ṫ). There is also a small increase in the microhardness, dynamic modulus of elasticity, and damping frequency in relation to the composition of the alloy and the microstructure.
Highlights
Materials engineering still faces major challenges in the modern world
This study evaluates the in situ production of two alloys, Al–0.8 Nb and Al–1.2 Nb, which were solidified in an ascending unidirectional solidification device to obtain a consistent microstructure
It can be observed that the Al–0.8 wt.% Nb alloy for alloys were 645.8° and 653.39° (Celsius), respectively
Summary
Materials engineering still faces major challenges in the modern world. There are a great variety of metal alloys, many of which are used due to their excellent properties. The importance of metallurgy field is evident, all metals, except for sintered parts, undergo a process of phase transformation and solidification during manufacturing, whether they are cast into shaped molds or produced into ingots. Alloys are studied with the aim to reduce weight, improve the combinations of mechanical properties, and predict their mechanical behaviour, such as damping capacity. Damping has practical engineering importance in limiting the amplitude of vibration at resonance conditions, and thereby reducing the probability of fatigue failure or it is capable to increase fatigue lives. Crankshafts, and overhead conductors are the typical applications where knowledge about damping capacity is crucial [1,2,3,4,5,6]
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