Designing NiTiAg shape memory alloys by vacuum arc remelting : first practical insights on melting and casting.
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2018
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Resumo
NiTi-based shape memory alloys are successful
owing to its capacity to cover specific applications
unreachable by binary NiTi. The additions of ternary, and
even quaternary, elements are intended to change specific
properties. Known for its antibacterial activity, Ag became
an alloying element in a search for a functional biomaterial;
however, the melting appears to hampering the system
exploration. A special melting procedure by vacuum arc
remelting was developed based on chemical and thermal
analysis, via EDS, XRF, and DSC, assessing the element
loss and ingot homogeneity, respectively. By alloy design,
different Ag content NiTiAg SMA were produced and
analyzed on as-cast condition. The melting procedure
developed involves specific feedstock cares and preparation,
melting, and some remelting steps. The measured
chemical composition slightly differs from the nominal due
to alloying element loss and the melting reaction thermodynamics.
Being the lower the possible, the remelting steps
were optimized to maintain the compromise between
chemical composition and compositional homogeneity
through the ingot, since the Ag content stabilizes along
them, also indicating a limited content possible to be
alloyed. Ag-yields are content-dependent, while the Ni:Ti relation is stable, being therefore the melting of NiTiAg
SMA better performed by VAR than other melting routes
under high vacuum conditions.
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Alloy design, Biocompatibility
Citação
SILVA, G. H. T. A. da.; OTUBO, J. Designing NiTiAg shape memory alloys by vacuum arc remelting : first practical insights on melting and casting. Shape Memory and Superelasticity, v. 4, p. 402-410, 2018. Disponível em: <https://link.springer.com/article/10.1007/s40830-018-0190-z>. Acesso em: 13 fev. 2019.