Bismarck Luiz Silva

Assessment of Tertiary Dendritic Growth and Its Effects on Mechanical Properties of Directionally Solidified Sn-0.7Cu-xAg Solder Alloys

Although commercial SAC107/207/307 alloys are being used as alternatives to traditional Sn-Pb solder alloys, there is a lack of studies emphasizing some metallurgical aspects, for instance, the different morphologies of Cu6Sn5 and Ag3Sn intermetallic compounds (IMCs) as well as conditions for the launch of tertiary dendritic β-Sn branches and their effects on localized mechanical properties. A wide range of cooling rates during solidification is normally associated with quite different microstructural length parameters. Hence, Sn-0.7 wt.%Cu-x wt.%Ag (where x = 1.0, 2.0, and 3.0) alloys were directionally solidified under transient heat flow conditions, undergoing cooling rates varying from 0.1 K/s to 32.0 K/s. This experimental study encompasses: primary, secondary, and tertiary dendrite arm spacings (λ1, λ2, and λ3) associated with the evolution of the tip cooling rate (

Dendritic Growth, Solidification Thermal Parameters, and Mg Content Affecting the Tensile Properties of Al-Mg-1.5 Wt Pct Fe Alloys

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Effects of cellular growth on fatigue life of directionally solidified hypoeutectic Al-Fe Alloys

T˙) during solidification; start and growth of tertiary dendrite branches; yield (σy) and ultimate tensile strengths (σu); elongation to fracture (δ); and the morphology of IMCs embedded in the Sn-rich phase. A single ratio between the cooling rate (

Tailoring Morphology and Size of Microstructure and Tensile Properties of Sn-5.5 wt.%Sb-1 wt.%(Cu,Ag) Solder Alloys

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MICROESTRUTURA, MICRODUREZA E PARÂMETROS TÉRMICOS DA LIGA DE SOLDA Sn-40%Bi-2%Ag

T˙) and the alloy silver content (C0-Ag) of 0.45 seems to be the parametric factor associated with the beginning of the growth of tertiary dendritic branches. SAC307 is shown to be the only alloy examined having λ3 along the entire casting length. Despite the presence of some tertiary branches in part of the SAC207 alloy casting, for both the SAC107 and SAC207 alloys, σu and σy are shown to increase with decreasing λ2, while the opposite trend is exhibited by the SAC307 alloy. It seems that the well-defined array of tertiary branches in such alloy, and consequently the more complex dendritic network, allowed the strength to increase despite the associated increase in λ2 and the change in the morphology of the Ag3Sn IMC from spheroidal to fibrous.

Correlation between microstructure and hardness of a Bi-1.5wt%Ag lead-free solder alloy

Hypoeutectic Al–Ni alloys are characterised by the formation of as-cast structures composed by a dendritic aluminium-rich matrix surrounded by a eutectic mixture (α + β), where α is the Al-rich phase and β is the Al3Ni intermetallics. The morphology, size and distribution of the intermetallic particles decisively affect the mechanical properties of these alloys. This study aims to determine experimental laws relating the primary dendritic arm spacing (λ1) and Vickers microhardness (HV) of hypoeutectic Al–Ni alloys. Upward unidirectional solidification experiments were performed in order to obtain castings with significant differences in the scale of microstructural parameters along the casting length. It was found that the microhardness values were directly influenced by both the amount of solute and λ1 and Hall–Petch-type equations relating the microindentation and λ1 are proposed.