NiSn4 formation during the solidification of Sn–Ni alloys

Metastable eutectic in Pb-free joints between Sn–3.5Ag and Ni-based substrates

“…Another reason may be that the presence of Au has clouded the interpretation, with researchers assuming this is AuSn4 with some dissolved Ni. However, our findings of eutectic NiSn4 when Sn-3.5Ag is soldered to Ni demonstrates that Au is not necessary for NiSn4 to form The nucleation and growth advantages of metastable NiSn4 over stable Ni3Sn4 are likely to be similar to those discussed previously for the binary Ni-Sn system [12].…”

“…The identity of the intermetallics was further confirmed by EBSD, where the NiSn4 EBSD patterns ( Figure 2B) could only be indexed as oC20-NiSn4 phase ( Figure 2D), consistent with NiSn4 being isomorphous to PdSn4, PtSn4 and AuSn4 [20]. Note that the NiSn4 has a very similar sheet-like morphology to the eutectic NiSn4 in binary Sn-Ni alloys [12,13]. Table 1 could only be indexed as oC20-NiSn4 or isotypic AuSn4, PdSn4 or PtSn4.…”

Nucleation and Growth of Tin in Pb-Free Solder Joints

“…Note that, in Figure 6, the substrate is 99.9% pure Ni to make the point that metastable NiSn4 forms when only Sn, Ag and Ni are present. Further details of metastable NiSn4 in Sn-3.5Ag/Ni and more complex Ni(P)/Au/Sn3.5Ag joints including phase identification by combining EBSD and EDX are given in our past work [47,48]. We have also shown that a binary metastable SnNiSn4 eutectic grows over a wide range of solidification conditions in the Sn-Ni system which is discussed in refs [48,49].…”

Influence of Bi additions on the distinct βSn grain structure of Sn-0.7Cu-0.05Ni-xBi (x = 0–4wt%)

“…Further details of metastable NiSn4 in Sn-3.5Ag/Ni and more complex Ni(P)/Au/Sn3.5Ag joints including phase identification by combining EBSD and EDX are given in our past work. [14][15][16][17]. Fig.…”