Fabrication of Nitinol Materials and Components

The Methods of Preparation of Ti-Ni-X Alloys and Their Forming

“…Subsequently, the composition of NiTi matrix (depletion by Ti) is significantly influenced by oxide and carbide intrusions and thus can cause degradation of functional and mechanical properties, which was also confirmed, e.g., in the study (Mentz et al, 2006). Other methods are hydridation, pulverization and mechanical alloying (Wu, 2002).…”

“…The deformation behaviour of SMA can probably be considered optimal in the temperature range near 800°C. Just these temperatures lie in the range where the alloys are workable and at the same time oxidation of their surface is not as massive as at higher temperatures (Wu, 2001). If forming temperatures are too high, the mentioned oxidation takes place and with increasing temperature the degradation of the material increases as well.…”

“…The melt during the arc vacuum melting therefore is not in contact with the graphite crucible (as it is in the case of the VIM technique with a graphite crucible/mould), thus a "more pure" product can be obtained using this method. The carbon content usually does not exceed 200 ppm (Dautovich & Purdy, 1965) or (Wu, 2001). For this technique a very high vacuum is required.…”

“…The temperature of intermediate annealing and its length will accordingly be the key parameters for the microstructure development. Generally it can be said that the temperature of intermediate annealing is lower than the temperature necessary for hot forming and usually is about 600°C (Wu, 2002).…”

Processing technologies of Ni-Ti based shape memory alloys

“…Appropriate arrangement of charge in the crucible is also very important at vacuum high-frequency induction melting [12,13]. It was established that if the surface of the crucible is covered with Ti disks, the content of carbon in produced alloy is reduced in comparison with the case of random arrangement of the charge.…”