The crystallographic growth directions of Sn whiskers

Stein, Jendrik; Welzel, U.; Leineweber, Andreas; Huegel, W.; Mittemeijer, E. J.

doi:10.1016/j.actamat.2014.12.004

Cited by 19 publications

(4 citation statements)

References 43 publications

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“…The most accurate method for the investigation of whiskers, and one that avoids damage of the whiskers, is a direct investigation of single whiskers on the growth substrate as described in the literature(Susan et al, 2012;Stein et al, 2015). However, this was not possible owing to the high density of grown whiskers on the growth substrate and the correspondingly small distances between them.…”

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confidence: 99%

Crystallography of γ′-Fe₄N formation in single-crystalline α-Fe whiskers

2020

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Gaseous nitriding of steel and iron can significantly improve their properties, for example corrosion resistance, fatigue endurance and tribological properties. In order to obtain a better understanding of the early stages of formation of the initial cubic primitive γ′-Fe4N, the mechanism and crystallography of the α–γ′ phase transformation was investigated under simplified conditions. Single-crystal α-Fe whiskers were nitrided at 823 K and a nitriding potential of 0.7 atm−1/2 for 20 min. The resulting microstructure and phases, as well as the crystallographic orientation of crystallites belonging to a particular phase, were characterized by scanning electron microscopy coupled with electron backscatter diffraction. The habit planes were investigated by single- and two-surface trace analysis. The α-Fe whiskers partly transform into γ′-Fe4N, where γ′ grows mainly in a plate-like morphology. An orientation relationship close to the rational Pitsch orientation relationship and {0.078 0.432 0.898}α and {0.391 0.367 0.844}γ′ as habit planes were predicted by the phenomenological theory of martensite crystallography (PTMC), adopting a {101}α〈101〉α shear system for lattice invariant strain, which corresponds to a {1 1 1}γ′〈1 12〉γ′ shear system in γ′. The encountered orientation relationship and the habit planes exhibit excellent agreement with predictions from the PTMC, although the transformation definitely requires diffusion. The γ′ plates mainly exhibit one single internally untwinned variant. The formation of additional variants due to strain accommodation, as well as the formation of a complex microstructure, was suppressed to a considerable extent by the fewer mechanical constraints imposed on the transforming regions within the iron whiskers as compared to the situation at the surface of bulk samples.

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Crystallography of γ′-Fe₄N formation in single-crystalline α-Fe whiskers

2020

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“…al explained the phenomenon that wedge type intermetallics can from easily at the columnar grains (with straight grain boundaries) due to the predominance of grain boundary diffusion over bulk diffusion at lower temperatures, while this phenomenon does not occur at horizontal grains [13]. The crystallographic orientation of the grains also affects the Sn whiskering susceptibility [14,15]. Jagtap et.…”

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The influence of the crystallographic structure of the intermetallic grains on tin whisker growth

Illés

Skwarek

Ratajczak

et al. 2019

Journal of Alloys and Compounds

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In this paper, the relationship between the crystallographic structure of Cu-Sn intermetallic grains and Sn whisker growth was investigated. In order to prevent the influence of the elements in the alloy composition and the effect of the soldering process on the formation of the intermetallic layer, 99.99% pure Sn was vacuum evaporated onto Cu substrates. The Sn layer thickness was sub-micron region (~400nm in average) to reach considerable and rapid compressive stress on the tin layer originated by the intermetallic formation. The samples were stored at room temperature for 1 month. Different types of whiskers (nodule and filament) and the layer structure underneath were studied with a scanning ion microscopy and transmission electron microscopy. It was found that not only the thickness of the intermetallic layer and shape of the intermetallic grains affects the whisker growth but the crystallographic structure of the intermetallic grains as well. The susceptibility of the Sn layer to whisker development is higher in those regions where the intermetallic layer is composed of monocrystalline grains instead of those regions, where it is composed of polycrystalline grains. This effect can be explained by the higher compressive stress generated by the monocrystalline intermetallics compared to the polycrystalline ones.

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“…7 The whisker interior atoms are completely aligned in the same direction and position, forming an ideal crystal without any defects and having a high tensile strength. 8,9 According to the previous reports, [10][11][12] the strength of iron whisker is more than 100 times of the ordinary iron strength. In addition, they have good chemical stability, anti-high temperature, anti-oxidation and EM wave absorption performance.…”

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confidence: 98%