Directional solidification of a Sn-0.2Ni solder alloy in water-cooled copper and steel molds: Related effects on the matrix micromorphology, nature of intermetallics and tensile properties

Xavier, Marcella G. C.; Cruz, Clarissa; Kakitani, Rafael; Silva, Bismarck Luiz; Garcia, Amauri; Cheung, Noé; Spinelli, José Eduardo

doi:10.1016/j.jallcom.2017.06.329

Cited by 19 publications

(19 citation statements)

References 36 publications

(37 reference statements)

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“…The mold plates were polished to ensure the same contact surface with the solidified metal for both alloys. In this way, the procedures and analyses performed resemble and corroborate with the recent solidification studies found in the literature [27][28][29][30][31][32][33][34][35][36].…”

Section: Introductionsupporting

confidence: 85%

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

Coutinho

Silva

Sousa

et al. 2019

Metals

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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.

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Section: Introductionsupporting

confidence: 85%

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

Coutinho

Silva

Sousa

et al. 2019

Metals

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“…For example, while much of the Sn-Ni phase diagram has been accurately determined recently [9][10][11], the least researched region is the Sn-rich end where the stable and metastable eutectic points exist [12][13][14]. Furthermore, while the crystal structure of metastable NiSn4 has been investigated [15][16][17], and the presence of eutectic NiSn4 has been confirmed after solidification [18][19][20], the conditions for the transition from stable to metastable eutectic growth have not been investigated.…”

Section: Introductionmentioning

confidence: 99%

Competition between stable and metastable eutectic growth in Sn-Ni alloys

et al. 2018

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Metastable Sn-NiSn4 eutectic can form in electronic solder joints and is a reliability concern. Here the competition between stable Sn-Ni3Sn4 and metastable Sn-NiSn4 eutectic growth is studied during unidirectional solidification. The stable and metastable eutectic points are measured, the dynamics of eutectic growth and the transition between the two eutectics is investigated by synchrotron radiography, and the crystallography of eutectic growth is measured by EBSD. It is shown that the Sn-Ni3Sn4 eutectic has a highly irregular morphology with diverging and converging rods because monoclinic Ni3Sn4 grows only along [010] without a reproducible orientation relationship (OR) with Sn. The metastable Sn-NiSn4 eutectic has a more regular broken-lamellar morphology and a reproducible OR with Sn. The critical velocity between the two eutectics is less than 1 µm/s which is discussed in terms of the small temperature difference between the two eutectic points and the kinetic growth advantages of the metastable eutectic.

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“…This gives an acceptable explanation of why although λ 1 and λ 2 are finer at regions closer to the cooled bottom of the Bi-20 wt% Sb alloy casting, the HV values are lower as compared with those of positions toward the top of the DS casting. Although hardness can be considered an important characteristic for TIM applications, further tests involving other important properties are necessary such as tensile properties, [64] wettability of the alloy against different substrates, [65] and the corresponding thermal interface resistance. [66]…”

Section: Resultsmentioning

confidence: 99%

Microstructure Growth Morphologies, Macrosegregation, and Microhardness in Bi–Sb Thermal Interface Alloys

et al. 2020

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Due to the rising demand for thermal management technologies within the electronics industry, there has been an increased emphasis on developing new thermal interface materials (TIMs) with enhanced performance. Despite Bi‐based alloys having exhibited promising potential as TIMs in microelectronics cooling applications, understanding the microstructure evolution of these alloys and the consequent effects on the resulting properties still remains an essential task to be accomplished. Herein, a directional solidification technique is used to investigate microstructural features and Vickers microhardness of Bi(5–20) wt% Sb alloys with a focus on the roles of alloy composition, solidification thermal parameters, and macrosegregation. The results show the formation of aligned Bi‐rich dendrites in a broad range of cooling rates from about 0.2 to 25 °C s−1. In contrast, as the alloy Sb content increases, two morphological transitions in the Bi‐rich matrix are shown to occur as follows: trigonal pattern → irregular shape → trigonal pattern. Then, primary and secondary dendritic arm spacings are related to growth and cooling rates through experimental equations. Finally, the occurrence of macrosegregation along the length of the Bi–20 wt% Sb alloy casting is shown to be a key factor associated with the variation of microhardness.

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Directional solidification of a Sn-0.2Ni solder alloy in water-cooled copper and steel molds: Related effects on the matrix micromorphology, nature of intermetallics and tensile properties

Cited by 19 publications

References 36 publications

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

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

Competition between stable and metastable eutectic growth in Sn-Ni alloys

Microstructure Growth Morphologies, Macrosegregation, and Microhardness in Bi–Sb Thermal Interface Alloys

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