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Invar, thermal properties

Thermal Properties. Selected data of thermal conductivity and thermal expansion of PGM and PgAg alloys are given in Tables 3.1-212-3.1-215, Fig. 3.1-273. FePd-alloys exhibit around the Fes Pd stoechiometry in the disordered state zero coefficient of thermal expansion (Invar effect) [1.281,282]. [Pg.373]

Low Expansion Alloys. Binary Fe—Ni alloys as well as several alloys of the type Fe—Ni—X, where X = Cr or Co, are utilized for their low thermal expansion coefficients over a limited temperature range. Other elements also may be added to provide altered mechanical or physical properties. Common trade names include Invar (64%Fe—36%Ni), F.linvar (52%Fe—36%Ni—12%Cr) and super Invar (63%Fe—32%Ni—5%Co). These alloys, which have many commercial appHcations, are typically used at low (25—500°C) temperatures. Exceptions are automotive pistons and components of gas turbines. These alloys are useful to about 650°C while retaining low coefficients of thermal expansion. Alloys 903, 907, and 909, based on 42%Fe—38%Ni—13%Co and having varying amounts of niobium, titanium, and aluminum, are examples of such alloys (2). [Pg.122]

In diamond C, it is the fact that the structure consists of sp covalent bonds only that accounts for its unique physical properties, such as the highest hardness of any material (Mohs hardness 10), small compressibility (1.7X10 cm /l ), the highest elasticity among any known material (4 6 X10 dynes/cm, bulk elasticity), large thermal conductivity (9 26 W/(deg cm)), and small thermal expansion coefficient (0.8 0.1 X10 at 20 °C, comparable to the value of invar). As a result. [Pg.167]

The final electrical connections to the STM can be done with copper wires. A small amount of helium is used as an exchange gas to anchor the temperature of the whole assembly to the cryogenic fluid. The body of the STM can be made out of copper, which will respond quickly to temperature changes for variable temperature measurements and provide a uniform temperature environment for the tunnel junction. One has to estimate the differential thermal contraction of the component parts to make sure that a tunnel junction separation set at room temperature is sufficiently large to prevent tip crash on cooling. Other materials like Macor or Invar , which closely match the thermal expansion properties of the piezoelectric transducers, are used as well but take more time to thermally stabilize. Some references are given in [6.30-6.43]... [Pg.137]

To conclude, several of the studied compounds, e.g. Nd2Fej4C, have an almost vanishing thermal expansion in the range 20-150°C, and these properties make them good candidates for applications as Invar-type alloys. [Pg.180]

Thermal expansion curves and magnetic properties of amorphous Cr Fe9o xZrio alloys have been investigated by [1994Lu] providing experimental evidence that the invar effect of these alloys is also related to the instabiUty of the ferromagnetism. [Pg.413]

Thermal expansion coefficients of invar 36 and free-cut invar 36 (containing S and P, or Se) between 25 and 900 are listed in Table 4.3-26 [3.17]. Some physical properties of Invar alloys are given in Table 4.3-27 [3.17]. [Pg.784]

Fe-Pd-Based Invar Alloys. Alloys of Fe—Pd (see Fig. 4.3-43) containing 28 to 31 at.% Pd show invar characteristics, as seen in Fig. 4.3-44 [3.41]. In order to obtain invar behavior, the alloys are quenched from the high terr5)erature y phase field such that phase transformations at lower temperatures are suppressed. As shown in Fig. 4.3-45 [3.41], the thermal expansion is strongly decreased by cold deformation, i. e., by disordering, lattice defects, and internal stresses. After cold working, an instability of the invar property is observed. [Pg.785]

Tablei .3-25 Thermal expansion coefficient, a and mechanical properties of invar aUoys for practical use [3.42]... Tablei .3-25 Thermal expansion coefficient, a and mechanical properties of invar aUoys for practical use [3.42]...
The deposition of Fe-Ni alloys is of industrial interest because these materials find applications in electronic devices (e.g. PC hard disk). The most popular alloys are Permalloy (soft magnetic properties) and Invar (veiy low thermal expansion). The magnetic and mechanical properties of Fe-Ni alloy can be designed by nanostructuring. Natter and Hempelmann (2003) used an electrolyte containing 40g/l NiS04, 20g/l (NH lCl, 20g/l Na citrate, 5g/l citric acid, lg/1 saccharin, 45 g/1 boric acid and a variable content of iron (II) ammonium sulfate. The pulse parameters used were t 2 ms, 48 ms and 250mA/cm2. For different concentrations of iron salts, alloys (crystallite size, 16-19 nm) with iron content between 0 and 71 mol% conld be obtained. [Pg.106]


See other pages where Invar, thermal properties is mentioned: [Pg.243]    [Pg.111]    [Pg.145]    [Pg.222]    [Pg.776]    [Pg.219]    [Pg.142]    [Pg.682]    [Pg.303]    [Pg.775]    [Pg.792]    [Pg.422]   
See also in sourсe #XX -- [ Pg.35 ]




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