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KMID : 0350519940470020997
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Journal of Catholic Medical College
1994 Volume.47 No. 2 p.997 ~ p.1007
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Superelasticity of Cast Shape Memory Ni-Ti Alloy
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Abstract
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Ni-Ti alloy has excellent corrosion resistance, biocompatibility, shape memory effect and superelasticity, so it has been used widely in biomedical fields. But it has difficulty in casting due to its high melting temperature and oxygen affinity
at
high
temperature. Recently it has been attempted to cast Ni-Ti alloy using new casting machine and investment.
The purpose of this study was to examine the superelastic behavior of cast shape memory Ni-Ti alloy and to compare the mechanical properties of the cast shape memory alloy with those of commercial alloys for removable partial denture framework.
Ni-Ti alloy(Ni 50.25%, Ti 49.75% : atomic ratio) was cast with dental argon-arc pressure casting machine and Type Ⅳ gold alloy, Co-Cr alloy, Ni-Cr alloy, pure titanium were cast as reference. Experimental cast Ni-Ti alloy was treated with
heat(500±2℃0 in muffle furnace for 1 hour. Transformation temperature range of cast Ni-Ti alloy was measured with differential scanning calorimetry. The superelastic behavior and mechanical properties of cast Ni-Ti alloy were observed and
evaluated by
three point bending test, ultimate tensile test, Vickers microhardness test and scanning electron microscope.
@ES The results were as follows:
@EN 1. Cast Ni-Ti alloy(Ni 50.25%, Ti 49.75% : atomic ratio) was found to have superelastic behavior.
2. Stiffness of cast Ni-Ti alloy was considerably lesser than that of commercial alloys for removable partial denture.
3. Permanent deformation was observed in commercial alloys for removable partial denture framework at three point bending test over proportional limit(1.5mm deflection), but was not nearly observed in cast Ni-Ti alloy.
4. On the mechanical properties of ultimate tensile strength, elongation and Vickers microhardness number, cast Ni-Ti alloy was similar was similiar to Type Ⅳgold alloy, Co-Cr alloy, Ni-Cr alloy and pure titanium.
With these results, cast Ni-Ti alloy had superelastic behavior and low stiffness. Therefore, it is suggested that cast Ni-Ti alloy may be applicated to base metal alloy for removable partial denture framework.
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