Coefficient of Expansion of Nickel

The change in size of cast-nickel between the customary pouring temp, and room temp, was found by D. H. Browne and J. F. Thompson to be about ¼ in. per foot - or 0.244 in, per foot. N. B. Pilling and T. Kihlgren also studied the casting shrinkage of nickel and its alloys. The coeff. of thermal expansion of nickel is very near to that of steel. This is of great practical importance, because it allows the two metals to be used in conjunction under conditions of varying temp, without distortion or relative changes of size or shape. W. H. Souder and P. Hidnert found that the average coeff. of expansion of ten samples of commercial nickel varied from 0.0000129 to 0.0000135 for the range 25° to 100°, and these data are approximately 10 to 20 per cent, greater than those for ordinary steel in the same range of temp. E. Gruneisen gave for a rod a metre long at 0°, up to 1000°, δl=1000{0.000013460(θ₂-θ₁) + 0.0₈3315(θ₂2-θ₁2)} mm.; and for the coeff. of expansion, he gave a=0.00001021 between - 190° and 17°, and 0.00001335 between 17° and 100°. H. Donaldson gave for the length of a rod at 6° which is unit length at 0°, l×10^-6=1+0.35θ+0.0016θ². H. Fizeau observed that the coeff. of linear, thermal expansion for nickel reduced by hydrogen and compressed is 0.00001279 at 40°. This value increases 0.0₈71 for each degree variation of temp. R. von Dallwitz-Wegner gave 0.0000357 to 0.0000444 for the cubic coeff. at 0°, and 0.0000419 to 0.0000468 at 100°.

H. le Chatelier gave 0.0000125 for the coeff. of expansion of nickel at ordinary temp., and 0.0000130 at 1000°; W. Voigt, for the expansion of unit length at 0°, 0.00001315+0.0000000413(θ-30); J. A. N. Friend and R. H. Vallance, 0.0000133, between 10° and 100°; H. Masumoto, 0.00001276 for electrolytic nickel, and 0.00001290 for Mond nickel; H. Masumoto and S. Nara, 0.00001358, between 30° and 100°; A. E. H. Tutton, for nickel reduced from carbonyl, 0.00001248+0.00000001480. L. Holborn and A. L. Day found for the average coeff. of expansion between 0° and 250° was 0.0000138; three days later, 0.0000139; and five days later, 0.0000142; between 250° and 375°, the coeff. Was 0.0000162; between 250° and 500°, 0.0000162, and five days later, 0.0000162; between 375° and 500°, 0.0000164; between 500° and 750°, 0.0000179, and five days later, 0.0000179; between 0° and 750°, 0.0000159, and the same five days later; and between 750° and 1000°, 0.0000192, and the same five days later. They represented the results by 0.000013460θ+0.0₈3315θ² for temp, above 375°. F. Henning gave 0.00001031 between -191° and 16°; and

	-198° to 16°	16° to 250°	16° to 375°	16° to 500°	500° to 750°	500° to 1000°
a	0.04101	0.04140	0.04147	0.04152	0.04176	0.04184

Observations were made by N. L. Mochel, A. Eucken and W. Dannohi, C. Williams, and P. Chevenard. P. Hidnert gave for the average coeff. of thermal expansion, a, for 99.94 per cent, nickel:

	25° to 100°	25° to 300°	300° to 600°	600° to 900°
a×10-6	13.3	14.4	16.5	17.8

There is an irregularity in the region near 350°. C. E. Guillaume obtained for purified nickel of commerce, 0.0₄12666+0.0₈542θ; and for various samples of commercial nickel, the coeff. ranged from 0.0₄12491+0.0₈702θ to 0.0₄655+0.0₈550θ. A. Krupkowsky gave for the mean coeff. of linear expansion of nickel, 8.10×10^-6 between -252.6 and 10°; 10.12×10^-6 between -183° and 10°; 14.04×10^-6 between 18° and 217°; and 15×10^-6 between 18° and 444°; whilst for the coeff. a and 2b in l=l₀(l+aθ+bθ²) he obtained between - 183° and 217°, a=11.86×10^-8 and 26=2.01×10^-6; and between 18° and 444°, a=12.83×10^-6 and 2b=1.03×10^-8. C. E. Guillaume observed that the thermal expansion of commercial nickel of 1911 was distinctly lower than that of some 1891 samples. J. Disch found for the linear expansion in mm. per metre between 0° and θ°:

	-190°	-78°	0°	100°	200°	300°
Expansion.	-1.885	-0.92	0	1.30	2.735	4.30 mm. per m.

Thermal Expansion of Commercial Nickel..

W. H. Souder and P. Hidnert found that the annealing of hot-rolled samples (Ni, 99.02; C, 0.08; Cu, 0.12; Mn, 0.22; Si, 0.16) generally caused a slight increase in the coeff. of thermal expansion. The average coeff. between 25° and 300° for samples containing 98.76 to 99.06 per cent, nickel are 0.0₄144 for the hot-rolled and 0.0₄145 for the annealed samples. For the range 25° to 600°, the coeff. of five hot-rolled samples varied from 0.0₄149 to 0.0₄156, and for five annealed specimens from 0.0₄154 to 0.0₄157. They represented their observations on the expansion and contraction of rods of commercial nickel by the curve, Fig. Only a slight irregularity was perceptible in the region of 350°, but no marked change occurs. This agrees with E. P. Harrison's statement that the effect with impure metals may be masked or modified by changes of a chemical nature. H. Wedding observed no essential difference in the thermal expansion of cast and wrought nickel.

Coefficient of Thermal Expansion of Nickel.

F. Simon and R. Bergmann's results for the coeff. of thermal expansion of nickel between -178° and 2° are indicated in Fig. F. L. Uffelmann's values of the coeff. of thermal expansion on heating and cooling curves are indicated in Fig. G. A. Tomlinson discussed the relations between the interatomic forces and the thermal expansion. E. P. Harrison found for purified nickel for temp, up to 300°, 0.0₄1280+0.0₅75θ+0.0₁₀35θ², and for the coeff. between 0° and 50°, 0.0₄128; 50° and 100°, 0.0₄136; 150° and 200°, 0.0₄151; 250° and 300°, 0.0₄174 300° and 350°, 0.0₄191; and 350° and 365°, 0.0₄205; 380° and 400°, 0.0₄191; 400° and 450°, 0.0₄189; 450° and 500°, 0.0₄192; and 500° and 550°, 0.0₄190.

Coefficient of Thermal Expansion on Rising and Falling Temperatures.

E. P. Harrison added that up to about 365°, the curve is regular, but between 365° and 380° there is an anomalous change in the expansion, whilst above 380° the curve is again regular and linear, with a different shape from the part which precedes it. No difference in the position or shape of the anomalous portion of this curve was noticed, whether the temp, was rising or falling, and in every case the wire returned after heating to its original length. There was no permanent elongation. The anomalous portion of the curve extends from 340° to 370°, and it is approximately the range over which changes occur in the thermoelectric force, electrical resistance, and magnetic permeability - the magnetic susceptibility vanishes at 370°. The anomalous change in the expansion was attributed to changes in the metal itself; though with impure metals, the true effect might be masked or modified by changes of a chemical nature. E. Janecke observed a break in the expansion curve at 347° to 360°, but M. Werner observed no abrupt change in volume. H. M. Randall's, and H. F. Colby's measurements indicated a critical region in the thermal expansion of nickel between 280° and 370°. W. F. Barrett observed an anomalous momentary expansion occurred in the cooling of a nickel wire, and this was coincident with a temporary, spontaneous re-heating of the wire. L. Holborn and A. L. Day said that a transformation occurs at about 370°, and that a rod originally 482.6 mm. at 0° was approximately 0.02 mm. shorter after each test. Observations were made by W. P. Davey. W. F. Colby measured the coeff. of thermal expansion of nickel in the neighbourhood of the Curie point, 374°, and the results are summarized in Fig. Whilst iron shows an anomalous increase in passing from the non-magnetic to the magnetic state, nickel shows an anomalous contraction. F. C. Powell calculated the contraction at 220° to be dl/l=-0.9×10^-4 - vide iron.

W. H. Souder and P. Hidnert also observed that after heating to 600° and cooling rods of commercial nickel to atm. temp., the rods were 0.004 to 0.065 per cent, shorter than before. E. P. Harrison observed no change with purified nickel; and H. G. Jones found that when nickel is quenched from 525°, it contracts for about 10 min., and for some hours it suffers very little change in length, but, after that, a gradual contraction occurs. A. Merz discussed the subject. A. Press, J. P. Andrews, E. Griineisen, and S. Ratnowsky studied the relation between the thermal expansion, compressibility, and at. vol.