Upward Unsteady-State Solidification of Dilute Al–Nb Alloys: Microstructure Characterization, Microhardness, Dynamic Modulus of Elasticity, Damping, and XRD Analyses

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...

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Main Authors:	Maycol Moreira Coutinho, José Ildon Saraiva Silva, Thiago Primo Sousa, Daniel Monteiro Rosa
Format:	Article
Language:	English
Published:	MDPI AG 2019-06-01
Series:	Metals
Subjects:	Al–Nb alloys microstructure characterization dendritic spacing unidirectional solidification
Online Access:	https://www.mdpi.com/2075-4701/9/6/713

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spelling	doaj-a9c4ca6ca9d44f87a4e3c1c5789c867f2020-11-25T01:49:38ZengMDPI AGMetals2075-47012019-06-019671310.3390/met9060713met9060713Upward Unsteady-State Solidification of Dilute Al–Nb Alloys: Microstructure Characterization, Microhardness, Dynamic Modulus of Elasticity, Damping, and XRD AnalysesMaycol Moreira Coutinho0José Ildon Saraiva Silva1Thiago Primo Sousa2Daniel Monteiro Rosa3Department of Mechanical Engineering, University of Brasília-UNB, 70910-900 Brasília, BrazilDepartment of Mechanical Engineering, University of Brasília-UNB, 70910-900 Brasília, BrazilDepartment of Mechanical Engineering, University of Brasília-UNB, 70910-900 Brasília, BrazilDepartment of Mechanical Engineering, University of Brasília-UNB, 70910-900 Brasília, BrazilAluminium 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 (<i>λ</i><sub>1</sub>) and secondary (<i>λ</i><sub>2</sub>) dendritic spacings for each alloy were given as a function of thermal variables. For Al−0.8%wt Nb, <i>λ</i><sub>1</sub> = 600.1(<inline-formula> <math display="inline"> <semantics> <mover accent="true"> <mi>T</mi> <mo>˙</mo> </mover> </semantics> </math> </inline-formula>)<sup>−1.85</sup> and <i>λ</i><sub>2</sub> = 186.1(<i>V</i><sub>L</sub>)<sup>−3.62</sup>; and for Al−1.2%wt Nb, <i>λ</i><sub>1</sub> = 133.6(<inline-formula> <math display="inline"> <semantics> <mover accent="true"> <mi>T</mi> <mo>˙</mo> </mover> </semantics> </math> </inline-formula>)<sup>−1.85</sup> and <i>λ</i><sub>2</sub> = 55.6(<i>V</i><sub>L</sub>)<sup>−3.62</sup>. 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 (<i>V</i><sub>L</sub>) and the cooling rate (<i>Ṫ</i>). 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.https://www.mdpi.com/2075-4701/9/6/713Al–Nb alloysmicrostructure characterizationdendritic spacingunidirectional solidification
collection	DOAJ
language	English
format	Article
sources	DOAJ
author	Maycol Moreira Coutinho José Ildon Saraiva Silva Thiago Primo Sousa Daniel Monteiro Rosa
spellingShingle	Maycol Moreira Coutinho José Ildon Saraiva Silva Thiago Primo Sousa Daniel Monteiro Rosa Upward Unsteady-State Solidification of Dilute Al–Nb Alloys: Microstructure Characterization, Microhardness, Dynamic Modulus of Elasticity, Damping, and XRD Analyses Metals Al–Nb alloys microstructure characterization dendritic spacing unidirectional solidification
author_facet	Maycol Moreira Coutinho José Ildon Saraiva Silva Thiago Primo Sousa Daniel Monteiro Rosa
author_sort	Maycol Moreira Coutinho
title	Upward Unsteady-State Solidification of Dilute Al–Nb Alloys: Microstructure Characterization, Microhardness, Dynamic Modulus of Elasticity, Damping, and XRD Analyses
title_short	Upward Unsteady-State Solidification of Dilute Al–Nb Alloys: Microstructure Characterization, Microhardness, Dynamic Modulus of Elasticity, Damping, and XRD Analyses
title_full	Upward Unsteady-State Solidification of Dilute Al–Nb Alloys: Microstructure Characterization, Microhardness, Dynamic Modulus of Elasticity, Damping, and XRD Analyses
title_fullStr	Upward Unsteady-State Solidification of Dilute Al–Nb Alloys: Microstructure Characterization, Microhardness, Dynamic Modulus of Elasticity, Damping, and XRD Analyses
title_full_unstemmed	Upward Unsteady-State Solidification of Dilute Al–Nb Alloys: Microstructure Characterization, Microhardness, Dynamic Modulus of Elasticity, Damping, and XRD Analyses
title_sort	upward unsteady-state solidification of dilute al–nb alloys: microstructure characterization, microhardness, dynamic modulus of elasticity, damping, and xrd analyses
publisher	MDPI AG
series	Metals
issn	2075-4701
publishDate	2019-06-01
description	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 (<i>λ</i><sub>1</sub>) and secondary (<i>λ</i><sub>2</sub>) dendritic spacings for each alloy were given as a function of thermal variables. For Al−0.8%wt Nb, <i>λ</i><sub>1</sub> = 600.1(<inline-formula> <math display="inline"> <semantics> <mover accent="true"> <mi>T</mi> <mo>˙</mo> </mover> </semantics> </math> </inline-formula>)<sup>−1.85</sup> and <i>λ</i><sub>2</sub> = 186.1(<i>V</i><sub>L</sub>)<sup>−3.62</sup>; and for Al−1.2%wt Nb, <i>λ</i><sub>1</sub> = 133.6(<inline-formula> <math display="inline"> <semantics> <mover accent="true"> <mi>T</mi> <mo>˙</mo> </mover> </semantics> </math> </inline-formula>)<sup>−1.85</sup> and <i>λ</i><sub>2</sub> = 55.6(<i>V</i><sub>L</sub>)<sup>−3.62</sup>. 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 (<i>V</i><sub>L</sub>) and the cooling rate (<i>Ṫ</i>). 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.
topic	Al–Nb alloys microstructure characterization dendritic spacing unidirectional solidification
url	https://www.mdpi.com/2075-4701/9/6/713
work_keys_str_mv	AT maycolmoreiracoutinho upwardunsteadystatesolidificationofdilutealnballoysmicrostructurecharacterizationmicrohardnessdynamicmodulusofelasticitydampingandxrdanalyses AT joseildonsaraivasilva upwardunsteadystatesolidificationofdilutealnballoysmicrostructurecharacterizationmicrohardnessdynamicmodulusofelasticitydampingandxrdanalyses AT thiagoprimosousa upwardunsteadystatesolidificationofdilutealnballoysmicrostructurecharacterizationmicrohardnessdynamicmodulusofelasticitydampingandxrdanalyses AT danielmonteirorosa upwardunsteadystatesolidificationofdilutealnballoysmicrostructurecharacterizationmicrohardnessdynamicmodulusofelasticitydampingandxrdanalyses
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Upward Unsteady-State Solidification of Dilute Al–Nb Alloys: Microstructure Characterization, Microhardness, Dynamic Modulus of Elasticity, Damping, and XRD Analyses

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