University of Groningen
De soortelijke warmte van ijzer, nikkel en hun onderlinge legeringen.
Zuithoff, Ate Johannes
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Publication date:
1939
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Citation for published version (APA):
Zuithoff, A. J. (1939). De soortelijke warmte van ijzer, nikkel en hun onderlinge legeringen. Groningen:
Koninklijke Van Gorcum
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SUMMARY
The specific heats of iron, nickel and iron-nickel-alloys at
different temperatures have been studied in this thesis.
Firstly the results of the measurements of the specific heats
of pure iron in a vacuum, beh';een 100° and 1500° c., are
described. Originally, a number of irregularities in the cp-i-curve
were observed. which apparently correspond to those already
found by NAESER. These irregularities proYed to disappear,
however, after the metal having been heated several times
at high temperatures. The supposition, that these phenomena
were due to gases, dissolved ill the metal, ,vas rendered more
probable by consecutive experiments.
From the experimental data obtained in the case of pure,
gasfree iron, the true specific heats ep were deduced. The values
were in completc accordance ,vith the results obtained by
KLINKHARDT, who used a direct method of measurement.
An abnormal increase of the specific heat starts already at
temperatures, a hundred degrees below the CURlE-point. More­
over, a characteristic discontinuity in the specific heat-curve
seems to occur at about 150'" c., which cannot be ascribed to
gases; the same discontinuity could also be stated in the measure­
ments of the linear thermal expansion, of the thermo-electrical
behaviour and of the electrical resistance, as a function of the
temperature. No change of the crystalline structure at
150o~200° C. could be found by means of X-ray-spectrograms.
In the second part the specific heats of iron-nickel-alloys,
with 10%, 20%, 30%, 40%, 50%, 70% and 80% nickel are
dealt with.
The so called "reversible" alloys (with 40% nickel and more)
prove to show an evident conformity of their cp-t-curves. On the
contrary, the "irreversible" alloys (with 0~30% nickel) ap­
parently manifest a deviating course of their specific heat­
curves. An appreciable discontinuity was found in the cp-t-curves
of alloys with 10% and 20% nickel at the y -'?- :7.-transition. An
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alloy containing 30 %nie
at its phase-transition.
liquid air was examined,
is completed at a low t
The true specific hea
values and compared fm
the relations between tt
The heat-content and
a composition of about
the occurence of a mini
of inuar (35 % nickel).
The validity of the
the additivity of the SPI
was once more checked.
approximative validity,
solid solutions.
The specific heats of y
from the data obtained
The relations betwee
these alloys with the
boundary-curves within
were studied.
Finally, the microsco]
investigation, were corr
ad iron-nickel-alloys at
cd in this thesis.
lts of the specific heats
:00° and 1500° C., are
larities in the cp-l-curve
spond to those already
s proved to disappear,
1 heated several times
, that these phenomena
:tal, was rendered more
~d
in the case of pure,
ere deduced. The values
Ie results obtained by
Id of measurement.
heat starts already at
the CURIE-point. 1\1ore­
the specific heat-curve
1 cannot be ascribed to
Ie stated in the measure­
of the thermo-electrical
~e, as a function of the
ystalline structure at
of X-ray-spectrograms.
;s of iron-nickel-alloys,
Yo and 80 % nickel are
alloy containing 30% nickel, displays strong retarding-phenomena
at its phase-transition. The influence of cooling this alloy in
liquid air was examined, and it appeared that the y -7> x-transition
is completed at a low temperature.
The true specific heats ep were deduced from the measured
values and compared for the different alloys, in order to discover
the relations between their heat-content and their composition.
The heat-content and the specific heat show a minimum at
a composition of about 30
nickel; this is in agreement with
the occurence of a minimal coefficient of expansion in the case
of inuar (35 % nickel).
The validity of the "rule of ::"iEU:'vIANN-Kopp", concerning
the additivity of the specific heats in intermetallic compounds,
was once more checked. In this case the rule proved to have an
approximative validity, in agreement with the occurrence of
solid solutions.
The specific heats of y-iron within these alloys were calculated
from the data obtained.
The relations between the changes in the specific heats of
these alloys with the temperature and the situation of the
boundary-curves within the diagram of the Fe-Ni-equilibria,
were studied.
Finally, the microscopic structures of the alloys, used in this
investigation, were compared with each other.
40% nickel and more)
heir cp-l-curves. On the
h 0-30% nickel) ap­
of their specific heat­
found in the cp-i-curves
le y -7> (L-transition. An
95