Iron-nickel superalloys

Iron-niekcl base superalloys were developed primarily from the stainless steels. In the United Slates, these alloys included 19-9 DL. lb-25-6, and A-286, Luler, higher nickel contents were employed to take advantage of the superior oxidation resistance of nickel and the beneficial effects of y -forming elements. All iron-nickel base superalloys rely on solid solution hardening lo some extent. 

Superalloys ate complex alloys containing up to 16 and more elements. There exist three basic types iron, nickel, and cobalt base alloys. Their important properties are ... 

Nickel-iron-chrome alloys include the iron base superalloys and the heat resistant castings (see previous section). Iron-base superalloys are an extension of the austenitic stainless steels and include alloys such as the Incoloy 800 series. They are used for piping and manifolds in refining, power generation and petrochemicals. 

Major industrial uses of tantalum include the production of electrical components (mainly capacitors), superalloys, tantalum carbide, and in the chemical industry (Cunningham 2000). Its physical properties make tantalum an important component of superalloys (produced by combination with cobalt, iron, nickel, and titanium) commonly used in the aerospace industry. In the chemical industry, tantalum s corrosion resistance is taken advantage of in the production of heat exchangers, evaporators, condensers, pumps, and liners for reactors and tanks (Cunningham 2000). The recycling of industrial and obsolete tantalum-containing scrap represents approximately 20% of the total tantalum consumption in the US (Cunningham 2000). 

The term superalloy is used for a group of nickel-, iron-nickel-, and cobalt-based high-temperature materials for applications at temperatures > 540 °C. It is useful to compare the main subgroups in terms of the strengthening mechanisms applied and stress-rupture characteristics achieved, as shown in Fig. 3.1-127. In this section iron-nickel- and nickel-based superalloys are covered whereas cobalt-based superalloys are dealt with in Sect. 3.1.6.3. Nickel-based superalloys are among the most complex metallic materials with numerous alloying elements serving particular functions, as briefly outlined here. 

Iron-, nickel-, and cobalt-based alloys used primarily for high-temperature applications are known as superalloys. The iron-based grades, which are less expensive than cobalt- or nickel-based grades, are of three types ... 

Detailed consideration of the structure of many of the advanced and complex alloys which are of considerable technological importance (high-strength titanium alloys, nickel-base superalloys, etc.) is beyond the scope of this section, other than to point out that no new principles are involved. Certain titanium alloys, for example, exhibit a martensitic transformation, while many nickel-base superalloys are age hardening. Similarly, cast irons, although by no means advanced materials, are relatively complex they are considered in Section 1.3 where graphitisation is discussed. 

The arrangement of the melting and vacuum spray chambers is critical for guiding the liquid metal to eject into the vacuum chamber. Difficulties exist in precisely controlling the expulsion of the liquid metal into the vacuum chamber. Therefore, flaky droplets may be formed in vacuum atomization. Although vacuum atomization was developed mainly for the production of high-purity nickel and cobalt based superalloy powders, it is also applied to atomize the alloys of aluminum, copper and iron. 

The distribution of nickel consumption by use in 1988 was as follows stainless and heat-resistant steel, 40% nonferrous alloys, excluding superalloys, 21% electroplating, 17% superalloys, 12% and other, 10%. Other uses include cast iron chemicals and chemical use electric, magnet, expansion alloys steel alloys, other than stainless steel batteries and ceramics. Eighty percent of nickel consumption was for the production of nickel metal and alloys (Kirk 1988a). 

Mew Materials and Processes. New materials and processes include aligned eutectics, oxide and liber-reinforced superalloys, intermelalhc compounds and other ordered phases including titanium aluminidcs. nickel aluminides. and iron aluminidcs. 

The United States has to import all the cobalt it uses. One of the most important applications of cobalt is in the production of superalloys. These superalloys consist primarily of iron, cobalt, or nickel, with small amounts of other metals, such as chromium, tungsten, aluminum, and titanium. Superalloys are resistant to corrosion (rusting) and retain their properties at high temperatures. Superalloys are used in jet engine parts and gas turbines. 

Superalloys Consist primarily of iron, cobalt, or nickel, with small amounts of other metals that are resistant to corrosion (rusting) and retain their properties at high temperatures. 

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