Tantalum-titanium alloys

Tantalum-Titanium Bishop examined the corrosion resistance of this alloy system in hydrochloric, sulphuric, phosphoric and oxalic acids and found that alloys containing up to about 50% titanium retained much of the superlative corrosion resistance of tantalum. Under more severe conditions, a titanium content of below 30% appears advisable from the standpoint of both corrosion resistance and hydrogen embrittlement, although contacting or alloying the material with noble metals greatly decreases the latter type of attack. Tantalum-titanium alloys cost less than tantalum because titanium is much cheaper than tantalum, and because the alloys are appreciably lower in density. These alloys are amenable to hot and cold work and appear to have sufficient ductility to allow fabrication. 

Nitric acid reacts with all metals except gold, iridium, platinum, rhodium, tantalum, titanium, and certain alloys. It reacts violentiy with sodium and potassium to produce nitrogen. Most metals are converted iato nitrates arsenic, antimony, and tin form oxides. Chrome, iron, and aluminum readily dissolve ia dilute nitric acid but with concentrated acid form a metal oxide layer that passivates the metal, ie, prevents further reaction. 

Olher mudern getter materials include cesium-rubidium alloys, tantalum. titanium, zirconium, and several of the rare-earth elements, such as hafnium,... 

Metallic materials with the exception of noble metals are also thermodynamically not stable in the acidic environment under the PEFC operating conditions and therefore subject to corrosion. Nevertheless, many different metals such as stainless steels, aluminum, aluminum composites, copper, nickel and nickel alloys, titanium alloys and even highly corrosion resistant materials used in chemical industry such as tantalum, hafnium, niobium or zirconium have been investigated with respect to applicability in PEFC with respect to corrosion resistance [68—71]. 

Cobalt chrome alloys, gold alloys, mercury amalgams, nickel-chrome alloys, nitinol alloys (shape memory and superelastic), stainless steels, tantalum, titanium, and titanium alloys... 

A majority of studies have been concerned with anodizing aluminum and its alloys, " " " although tantalum, " titanium, zirconium, and other transition and coinage metals have been of interest. The Italian school under Conte has been particularly active in these investigations which have mainly centered on nitrate melts, over the temperature interval 343-723 K. A bisulfate mixture is used in a Japanese commercial process. " Table 4 shows some of the melt systems that have been studied. 

More than 100 different coronary stent types are known. Many of them are still available others have been suspended but can still be found in patients that were treated in the past. Stents can be composed of different material. Most products are made from stainless steel. Cobalt-chromium is another material used frequently. Tantalum and nitinol (nickel-titanium alloy) are also being used but less frequently. Stents from biodegradable materials such as magnesium are being evaluated in phase III studies. The degree of artifacts produced by stents from different materials depends largely on the atomic number of the material. Consequently, tantalum causes the strongest artifacts, followed by steel, cobalt-... 

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