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Mechanical and Functional Properties of Laser-Welded Ti-55.8 Wt Pct Ni Nitinol Wires

“…[15][16][17] Hence, the asreceived wires were immersed in an acid solution to remove surface oxide and contaminants. Since prolonged acid immersion can excessively reduce the wires' cross-sectional diameter, a preliminary study was con- ducted to analyze these effects and select an appropriate treatment time.…”

“…[14,15] Similar observations were reported during the production of Nitinol ingots. [16] In general, inclusions of carbon and oxygen are kept to a minimum, because Ti-Ni-O intermetallic compounds (IMCs) have lattice structure of large misfits with Nitinol, creating incoherent precipitates that can cause premature failure. [17] B.…”

The effect of processing routes on the structure and properties of magnesium–TiNi composites

“…A 1% increase in the Ni content results in a drastic decrease (more than 100 1C) in the M s transformation temperature. Although the precipitation increases the transformation temperatures, oxidation decreases the transformation temperatures due to the formation of Ti 4 Ni 2 O phase [21]. Because the oxide phase consumes more titanium in the matrix, the transformation temperature decreases as the relative nickel content of the matrix is increased.…”

“…Apart from these, in some TiNi powders near the interfacial regions, where titanium is depleted, new strain-free nickel rich phases with 20-30 nm dimensions were also detected. It is known that the depletion of titanium, as a result of the oxidation or enrichment of nickel in the matrix, induces the formation of a nickel-rich TiNi 3 phase [30]. The EDS analysis taken along these phases in the present study revealed 70.2 at% nickel and 29.8 at% titanium, which is equivalent to the chemical composition of TiNi 3 phase; this may be due to the starting powders and/or may form during processing, due to the oxidation of the TiNi powder surfaces.…”

Phase Transformation Behavior of Porous TiNi Alloys Produced by Powder Metallurgy Using Magnesium as a Space Holder

“…Since during its formation Ti atoms are consumed twice as much compared to Ni atoms in the matrix, in the presence of excess oxygen to form Ti 4 Ni 2 O, the TiNi 3 phase also appears in the Ni enriched matrix. [43] In summary, it is not possible to produce single-phase TiNi alloy in even slightly oxygenous environments. Partial pressure of oxygen must be less than 5 9 10 À25 atm at 1373 K (1100°C) to prevent TiO 2 formation at the surface of the TiNi samples according to the calculations based on the thermodynamics data given in Reference 44.…”