Effects of Growth and Cooling Rates Via Horizontal Solidification of an AlCuNb Alloy: A Thermal, Microstructural and Mechanical Analysis

Primary interphase dendritic growth via unsteady-state horizontal solidification of an Al-Cu-Nb alloy

“…As can be seen, the macrostructure consisted of fine equiaxed grains along the length of the ingot, and finer and coarser dendritic microstructures was obtained for positions closer and farther from the heat transfer interface (cooling base) as growth and cooling rates became higher and lower, respectively. Dillon et al [15,16] carried out thermal analyzes resulting from the horizontal solidification process under the same conditions assumed in this work and proposed mathematical expressions to correlate the thermal solidification parameters (VL and TR) as a function of the position in the as-cast ingot, given by VL=2.17(P) -0.3 and TR=82.8(P) =0.7 . It could be noticed that the VL and TR values gradually decrease with the advance of solidification due to the increasing formation of the solid layer that promotes resistance by thermal conduction, thus influencing the dendritic microstructures shown in Figure 2b.…”

“…The studied alloy, the horizontal solidification experiment, and thermal analyzes to determine the desired thermal parameters (VL and TR) were obtained in works recently published by our research group [15,16]. During the preparation of the alloy, because Nb has a very high melting point (~ 2468 °C), which is much higher than that of the other constituent elements of the alloy, Al and Cu, its insertion into the liquid metal occurred last, given the diffusion mechanism under high temperatures for its integration as the second solute in the liquid matrix of the solvent (Al) [16].…”

“…The thermal data acquisition system used during the solidification process consisted of a temperature recorder (FieldLogger) connected to a computer and data recording software that receives these values and converts them into a notepad in the form of ordered pairs (T, t). This notepad was imported into another data processing software (OriginPro), where the thermal solidification profiles were plotted, and from the same, the experimental VL and TR values were determined [6][7][8][9][10]15,16,23].…”

“…Cross-sectional as-cast samples from the solidified ingot resulting from the work of [15,16] were prepared, considering positions from the heat transfer surface of the ingot mold of the watercooled solidification device, aiming to evaluate the effects of VL and TR on the evolution of the dendritic microstructure, which was quantified by the interphase spacing of the primary dendritic arms (1α) of the Al-rich phase. The measurement of 1α, shown schematically in Figure 1, according to References [24,25], was based on the neighborhood criterion.…”

“…Studies have been carried out with alloys of the duralumin series, which are binary, ternary, or quaternary multicomponent alloys, which have in their composition copper with the addition of silicon, magnesium, titanium, nickel, and others that provide aluminum with excellent mechanical resistance at high temperatures, especially with heat-treated alloys. Niobium, for example, has been one of those elements that, in recent studies, has been investigated as an added element in Al alloys [14][15][16][17][18][19][20][21][22].…”