%0 Journal Article
%T Nickel-Containing Alloys for Medical Application Obtained by Methods of Mechanochemistry and Powder Metallurgy
%A D. D. Radev
%J ISRN Metallurgy
%D 2012
%R 10.5402/2012/464089
%X The methods of mechanochemistry, in combination with cold pressing and pressureless sintering, were used to obtain the most popular nickel-based and nickel-containing alloys used in dentistry and implantology. It was shown that the intense mechanical treatment of Ni, Ti, and Cr powders used as reagents, and the application of the above-mentioned simple powder metallurgical technique for densification allows obtaining NiCr and NiTi alloys with controlled structural properties. The nickel-based dental alloys obtained by mechanically activated sintering possess excellent mechanical, technological, and aesthetic properties. These alloys are suitable as dental restorative materials and for production of porcelain veneered constructions like crowns and bridges using the so-called metal-to-ceramic dental technique. It was shown that the method of mechanically assisted synthesis allows obtaining nanosized NiTi alloy at significantly lower temperature in comparison with the traditional high-temperature alloying. It was also shown that after 40 hours intense mechanical treatment of reagents, a direct synthesis of NiTi alloy proceeds. The product has excellent sinterability which enables to produce bodies with controlled porosity appropriate for application in implantology. 1. Introduction The range of traditional application of nickel-based alloys covers different areas that require high performance at elevated temperatures. The formation of continuous matrix austenitic phase, that usually contains various percentages of Cr, Mo, W, Fe, and Co, the presence of coherently precipitating phases, and carbide or boride grain boundary segregates gives possibilities to form variety of alloys working at extremely high temperatures subjected to a combination of mechanical stresses and thermal shocks. The large number of Ni-based superalloys and the multiplicity of their properties and areas of application are a good example in this respect. Due to the attractive combination of good mechanical properties, chemical resistivity and biocompatibility Ni-based alloys also find a broad application in the fields of dentistry and implantology. Nickel-chromium and nickel-titanium alloys are the most popular representatives in these two medical branches. 1.1. Nickel-Chromium Dental Alloys Dental alloys could be categorized as noble, containing as a main element gold or palladium and base nickel or cobalt metal alloys [1]. The significant increases of the noble metals price since 1960s stimulate the development of nonprecious nickel-based dental alloys. Nowadays Ni-based alloys used
%U http://www.hindawi.com/journals/isrn.metallurgy/2012/464089/