An X-ray determination of the thermal expansion of α-phase Ag–Ga alloys at high temperatures

Halder, S. K.; Gupta, S. P. Sen

doi:10.1107/s0567739474001951

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“…The lattice parameters increase non-linearly with temperature and from least-squares fits of the experimental data the coefficients of linear thermal expansion (:t) have also been calculated. The values of :t are also shown in Table 1 and are found to decrease linearly with increasing temperature for all four compositions covering the solid-solution range.The lattice expansion behaviour in this alloy system resembles those ofAg Ga and Cu Ga (Halder & Sen Gupta, 1974, 1975 alloy systems. In these cases the lattice expands non-linearly with increasing temperature, but the rate of expansion decreases with increasing temperature, resulting in a net linear decrease in ~.…”

mentioning

confidence: 69%

“…The lattice expansion behaviour in this alloy system resembles those ofAg Ga and Cu Ga (Halder & Sen Gupta, 1974, 1975 alloy systems. In these cases the lattice expands non-linearly with increasing temperature, but the rate of expansion decreases with increasing temperature, resulting in a net linear decrease in ~.…”

mentioning

confidence: 69%

“…Relatively few measurements of thermal expansion exist for alloys (both binary and ternary) and therefore a programme has been undertaken to study the lattice expansion of copper-and silver-based alloys (De, 1969;Halder & Sen Gupta, 1974, 1975 and semiconducting materials (De & Sen Gupta, 1982) at high temperatures by an X-ray diffraction method.…”

Section: Introductionmentioning

confidence: 99%

“…The alloys, which contain 5-8, 9.2, 15.8 and 18.2 at.% AI, have been investigated in the temperature range 303-928 K. ~av for the four compositions are 20-41, 19.69, 19.93 and 20-37 x 10 6 K-1Relatively few measurements of thermal expansion exist for alloys (both binary and ternary) and therefore a programme has been undertaken to study the lattice expansion of copper-and silver-based alloys (De, 1969;Halder & Sen Gupta, 1974, 1975 and semiconducting materials (De & Sen Gupta, 1982) at high temperatures by an X-ray diffraction method.Four Ag-AI alloys containing 5"8, 9.2, 15.8 and 18.2 at.% AI were prepared from spectroscopically pure Ag and AI (metals supplied by Johnson Matthey and Co., Ltd, London). Accurately weighed quantities of the constituent metals were placed in graphite crucibles which were sealed under vacuum in quartz capsules.…”

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confidence: 99%

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An X-ray determination of the thermal expansion of α-phase Ag–Al alloys at high temperatures

Pradhan¹,

De²

1986

J Appl Cryst

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The lattice expansion of four Ag-AI alloys of different composition has been determined by X-ray measurements. The alloys, which contain 5-8, 9.2, 15.8 and 18.2 at.% AI, have been investigated in the temperature range 303-928 K. ~av for the four compositions are 20-41, 19.69, 19.93 and 20-37 x 10 6 K-1Relatively few measurements of thermal expansion exist for alloys (both binary and ternary) and therefore a programme has been undertaken to study the lattice expansion of copper-and silver-based alloys (De, 1969;Halder & Sen Gupta, 1974, 1975 and semiconducting materials (De & Sen Gupta, 1982) at high temperatures by an X-ray diffraction method.Four Ag-AI alloys containing 5"8, 9.2, 15.8 and 18.2 at.% AI were prepared from spectroscopically pure Ag and AI (metals supplied by Johnson Matthey and Co., Ltd, London). Accurately weighed quantities of the constituent metals were placed in graphite crucibles which were sealed under vacuum in quartz capsules. The melting was done in a muffle furnace and the capsules were constantly shaken. The resultant ingots were then homogenised by keeping the capsules at 873 K for ten days. The lattice parameters of the ingots were determined from diffractometer tracings of the annealed powders, obtained by hand-filling the ingots and sieving the powders through a 325 mesh screen, and heat-treated at 773 K for 8 h in evacuated quartz tubes. The actual compositions of the alloys were determined by interpolating these values of lattice parameters from the lattice parametercomposition curve obtained by Foote & Jette (1940). A portion of the annealed powders was then sealed in thinwalled quartz capillaries (internal diameter --,0.3 mm) and X-ray photographs were taken with a standard Unicam 19 cm high-temperature powder camera using Cu K~t radiation. Each photograph was followed by duplicate runs to show reproducibility of the data within the range of experimental error. The temperatures of the camera and furnace were measured accurately within +_ 2 K with the help ofa Pt-PtRh thermocouple, previously calibrated by measuring the lattice parameters of pure silver (Quader & Dey, 1962). The line positions were accurately measured at least three times each from the high-angle edges of the films, using an optical device (Rich, Seifert and Co., Hamburg) with a precision of 0.1 mm. To minimize systematic errors in the measurements, lattice parameters were obtained by using the Nelson & Riley (1945) extrapolation function and the precision in the values of the lattice parameters was found to be within _+ 0.0004 A. Table 1 contains mean values of the lattice parameters obtained from two sets of photographs for each temperature for four Ag-AI alloys in the temperature range 303-928 K. The initial and final room-temperature lattice-parameter values (also shown in Table 1) show that there is no appreciable loss of solute AI during repeated heat treatment. The lattice parameters increase non-linearly with temperature and from least-squares fits of the experimental data the coefficients of line...

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confidence: 69%

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confidence: 69%

Section: Introductionmentioning

confidence: 99%

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confidence: 99%

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An X-ray determination of the thermal expansion of α-phase Ag–Al alloys at high temperatures

Pradhan¹,

De²

1986

J Appl Cryst

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“…X-ray measurements of lattice spacing in the temperature interval 26-522°C for four Ag-Ga alloys, and in the temperature interval 30-514 °C for four Cu-Ga alloys have been reported earlier in parts I and II, respectively, by Halder & Sen Gupta (1974, 1975. The present investigation, referred to as III, reports the X-ray measurement of lattice expansion on three Ag-Ge alloys from 30 to 595°C and two Cu-Ge alloys from 25 to 611°C, all the alloys being in the solid-solution range.…”

mentioning

confidence: 63%