Hydrogen in metals

197 Pages·1948·53.791 MB·English

by  D.P. Smith

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HYDROGEN IN METALS
HYDROGEN
IN
METALS
By
DONALD MITH
,
THE UNIYERSITY OF CHICAGO PRESS
CHICAGO· ILLINOIS
THE UNIVERSITY OF CHICAGO COMMITTEE ON
PUBLICATIONS IN THE PHYSICAL SCIENCES
*
WALTER BARTKY JOSEPH E. MAYER
FOREWORD
WARREN C. JOHNSON CYRIL S. SMITH
WILLIAM H. ZACHARIASEN THIS book is the second in a series of monographs on various aspects of
the science of metals lhat was established under the joint auspices of the
l.nstitute for the Study of Metals and the University of Chicago Press.
The Institute was established by the University of Chicago late in 1945 to
bring to the old field of metallurgy some of the stimulus resulting from
close contact with physicists, physical chemists, and others, and to bring
to men with more basic approach and interests some of the advantages of
contact with the vast empirical knowledge of metals and an awareness of
possible end-use of their research. It soon became apparent that the de
sired cross-fertilization between fields could be promoted as much by print
281 0'1 7
AS by proximity, and the monograph series was therefore established to
GGq further the aims of the Institute. Works by any author are eligible, pro
vided that they deal in a competent manner with some aspect of metal
$ ",5 science or related fields. Three k.inds of monographs are to be encouraged:
critical reviews of particular topics that seem ripe for further research
the kind of work that generally will be written by a scientist as he makes a
detailed survey of the status of the field before undertak.ing intensive
original work on it; extended summaries written after prolonged work in a
specialized field at the time when a scientist wishes to record his work in
perspective as a basis for future investigations by himself and others; and,
lutly, books discussing the application of particular scientific principles or
lechniques to metallurgy and related subjects.
The present book, Hydrogen in Metals, is most timely because of the
increasing realization of the importance of hydrogen in influencing the
ductility and other mechanical properties of steel and the suspicion that
it may be concerned in the apparently anomalous behavior of many other
metals and alloys. The author does not, however, discuss the industrial
aspects of his subject, though his work will certainly provide a basis for
many technical studies. The book is a critical correlation of a:ll significant
THe UNIVERSITY OF CHICAGO PRess, CHICACO 37
Cambridge University Press, London, N.W. I, England published data relating ~o the physical chemistry of hydrogen systems
The University of Toronto Press, Toronto 5, Canada with all the metals. This bas been the author's interest for many years,
and the contributions of his laboratory constitute an important part of the
Ct1f1.J.,igAI 1948 by Tht U.i"mily oj CItUQgo. All rj,hh,nnwd
literature reviewed herein. Dr. Smith bas come to believe that lattice
Puhli~hM 1943. S«QN/ lmpTlnirm 1958. c-,,0.1I6.w1 pril'lltd by
TIll!: UNIVJI.IWTV OF CHICAOQ PIlus, C/II'all', lIIilllJis, U.S.A.. defects are frequently dominant in detennining the behavior of a given
hydrogen-metal system and his speculations on the infiuence of structure
l
v
FOREWORD
and strain on such systems are worthy of close attention in view of the
present widespread interest in crystal imperfections and their influence on
physical, chemical, and mechanical properties. The occlusion and difTusion
of hydrogen is potentially an important tool for studies of various types of
PREFACE
crystal defects.
As a bibliogmphy the book will prove of great value- few authors have THIS monograph deals with all the modes of absorption or retention of
attempted to attain such completeness in covering a subject of this type; hydrogen by massiue solid metals- the phenomena which are still most
as a critical discussion of an important and broadening field it provides comprehensively and objectively described by Thomas Graham's term
not only a convenient summary of the present status but also an excellent Hocclusion"- and with the causes and direct consequences of such occlu~
basis and stimulant for further work. sian of hydrogen.
CyltlL STANLEY SYITII, Chairmall The literature of these matters is fully assembled and collated and is
CHARLES S. BARRETT considered in the light of the now numerous studies of the effects of occ1u~
EARL A. LONG sian on lattice parameters, on the diffusion of the lines of the X-ray spec
lrum, and on electrical resistance, magnetic susceptibility, and other
CLARENCE ZENER
Commiffee OIl M ollographs properties.
ItlStitllte jor the Stlldy oj Metals When examined, this literature presents an extensive and minutelyar
ticulating body of empirical material, self-consistent and relatively in
depcnrlent of rlOOlldinns derived from other fields of investigation. In par
ticular, it merits consideration as supplementing the indications obtain
!\ble from the unaided application of X-ray analysis to metallic structure
nnd its changes, in the realm of dimensions where these arc of chief con
cern, and as yielding evidence with respect to the structure sensitivity
which characterizes not only occlusion but many of the most important of
metallic properties.
The view here presented is essentially empirical and is confined to the
experimental observations and such deductions as seem directly to follow.
Although memoirs and more extended works concerned with the highly
theoretical aspects of solution and diffusion of hydrogen in metal are duly
noted in topical bibliographies, they are discussed only in certain special
relations, as questions arise regarding the compatibility of assumptions
rlecessary to these treatments, with the evidence here assembled.
The subject of occlusion is in tbe broadest sense related to all those
topics of physics, chemistry, or metallurgy in which interactions between
hydrogen and solid metal are involved; but it is evident that general con-
1I1deration of many of these matters has no place in a restricted mono
graph. All topics, such as adsorption and catalysis, wbich are already the
Aubjects of comprehensive special works have therefore been omitted,
lave for the most necessary incidental mention, while, as is more fully ex
plained in chapter i, certain direct consequences of occlusion have also
been excluded or briefly dismissed. Publications dealing with subjects of
vii
PREFACE
the type last Ilamed have nevertheless been included in the General
Bibliography, which forms an essential part of the monograph.
With respect to this annotated bibliography of some 1,470 references,
it is to be said that it has been made as nearly complete as seemed feasible TABLE OF CONTENTS
upon its primary subject of occlusion, while it includes, in addition, many
references on closely connected matters which are taken up in text or notes. TABLE 1: PERIODIC SYSTEll AND Qca.USIOS ,i
Although it has been possible to include some later references in the
NUKlIERING AND SYMBOLS liii
Bibliography, the literature has been discussed only to about the end of
the year 1946. 1. INTRODUcnOS •
D. P. S.
n. OccLl.1S10S ASO OccLUDING .METALS 2
FRICI(. CUEMICAL LABORATORY
f"luNCETON, New]'u!w.v III. OccUJSIVE CHAltACTERlSTICS: VARIABLE PEIUlEAJIlLtTY "NO DIHEN
SUMM"", 1947
SJONAL CHANGES 5 ~
IV. THe COURSE AND RATE OJ' OccLUSION 1
V. OcCLUSiVE CAPACITY AND SOLUBILITY 21
VI. OcCLUSlO~ I~ ENDorUERlucOccLUDEII.S: 1'£, CO, Nl; CR, Cu, P1:i AG .3.1
vn. •
OCCLUSIO!Il BY PAU ADlU).\ AND TIlE PHASES ASD PHASE-FIELD LnrlTs OF
PALLADIUM-HYDROGEN
12.
VIII. TIn: ELECTUCAL CoNDUCTION 01' Po-H .
•
IX. ELECTRODE POTENTIAL AND TlfE OVERSTEPPLNG,PllENOIBNA 01' Pu-H 145
X. EXOTHERl41C OccLUSION BY MET"LS OTHER THA~ PALLADtull:
1'1, ZR, Til; V, CB, TA; Ui LA, CEi PR., No; SA 15<1
Xl. A~OllALOUS At'.""D NO~OCCLUDING METALS: h1N, Ca(?), Mo{??)i PLATI
NUM GROUP: Au, W; THE "B" METALS. 182
XH. TERSA.IlY HYDR.OGES ALLO\'S . 193
x lrr. :MAGNETIC AND ClIElilCAL RELATlO~S 214
XlV. SURVEY: ThE :METAL A~D THE HYDROGEN 229
SUPPLEJ.!E:.-rAII.Y NOTES 245
(if.N"ERAL BIBLIOGRAPHY (serving atso os AlTTIION, ISUEx) 293
SUBJECT I:s-ollx (indlldillg 'EOPICS "NO SYSTEIoIS) 363
r
~&l',,"
PLATE I • 234 c
36;
i,
/,
T ABLE I. PER 100 IC SYSTEM & OCCLUSION.
Leot ... o rOil e ·El(OTHC .... C OCCLUDC_; e-'EHOOTHCIWtC OCCLUDEII;
'H C - MCT ( XNOH-OCCLUOU; .,-(, A-U "',...,UT' ....T tD, 'f;"
ru- - NO,. -UtTALS
----
La C. Pr Nd Sa Be B C N 0 F Ne
. e e e e e
f-- ti ----
Na R .... e c .... ," "'[T"'L~ Mg AI Si P S CI Ar
.. .. ..
K Ca Sc Ti V C...r. Mn F..... C..o. Ni Cu Zn Ga Ge As Se Br Kr
A e e e e ..
Rb Sr Y Zr Cb M...o. Ma Ru Rh Pd Ag Cd In 5 n 5 b Te I X
e e e
A A III Ii!)
Cs Ba ~ HI Ta W Re Os Ir P...I. Au Hg T I Pb Bi Po 85 Rn
A e X A iii) iii) X
87 Ra Ac Th Pa U I.
" e " ED
-
,-__'- , I 1 .. !> 6 7 a e 10 II 12 13 '4 15 16 17
a
A.-U, T,\l.S C-M[TALS -"[TALS
NUMBERING AND SYMBOLS
Chapters are designated by lower-case Roman numerals, as ii.
Sections are de!oignated by Arabic numerab, on a "decimal" system, the first fig
l,U"C(s) being the chapter number, thus:
9.4 is section 4 of chapteT i;L
9.4.1 is a section inserted between 9.4 and 9.5.
Notes art designated by the number of the section to which they relate, with added
letter, thus:
9.4.11. is the first note to section 9.4.
Figures, equations, and table! (except Table I) are numbered from the section or
note in which they occur, thus:
Figure 9.4-1 is the first figure in section 9.4.
Table 9.4-2 is the second table in section 9.4.
Equation 9.4.11.-3 is the third equation in note 9.4.11..
H represents hydrogen, without regard to its condition.
H. represents molecular (or gMCOus) hydrogen !mIy.
A, B C, ltf, and V are meASUres of oocIusion or hydrogen--content, e.xplained in 5.0.11..
t
In systems having more than one solid phase (as Pd-H):
a. is the hydrogen-rich phase of "lenninal solid solutions."
a.~ is the mean hydrogen concentration of the Q-pha.5e.
ILo is the saturntion concentration of the ct-phase.
a.~ is the value duri1lg oosurption of ct., when the surface of the ct-phase reaches the
value cto (- a.-phase limit IfIo.r absorption).
a.:
is the (displaced) value of during el'OluJicm.
13 is the hydrogen-rich secondary phase.
It, is the inferior limit of concentration of the ~ha.st during ahlorptioll.
fJ' i! the (displaced) value of fJ. during etoIutimt.
" i~ the penetFd.tLOn limit, or mean concentration at which the absorbing maS$ of
metal beromes impregnated with hydrogen to it.~ lll"is or center (dependent on
tineness of division) . •
" is the magnetic limit or mean concentration, aoove which (in exothennic sy:;tcms)
occlusion no longer affect! magnetic susceptibility (probably identical with ,,).
xiii
T
iNTRODUCTION
1.0 Hydrogen has a unique ability to penetrate many solid metals di
rectly from its ordinary gaseom; state when the metals arc in suitable con
dition; and its penetrative ability is much enhanced by ionization or by
dissociation to atoms, so that in such special states it enters metals which
arc otherwise impervious. In addition, it may be retained by less pene
trable metals when these are deposited as solids in certain ways.
Qur subject is expressly limited to these various types of occlusion and
their causes and consequences and is further restricted only by the exclu
sion of a few minor topics upon which present information is scarcely suffi
cient to justify detailed discussion. Topics of this kind, such as the cffect
of hydrogen on thermo-e.m.f., are included only in the Subject Index and
the General Bibliography, whence their brief literature may readily be
found.
Despite these restrictions, the subject of occlusion is extensive and
varied. We therefore begin our treatment with a general consideration of
its occurrence and types in chapter ii and an anticipatory survey of its
outstanding characteristics in chapter iii. These are followed, in the order
shown in the Table of Contents, by discussion of the' principal related
matters and of all investigated metal-hydrogen systems. In the course of
these discussions there becomes apparent the close relationship between
occlusion and the state of strain of the metal and the readiness with which
even the complicated hystereses and overstepping phenomena lend them
selves to interpretation in terms of an expanding and contracting system
of widened lattice-spacings or rifts. Finally, in chapter xiv, the cumulative
evidence is summarized.
1.1 For greater continuity of treatment, some particularly detailed dis
cussions, which were deemed nC(essary, have been relegated to the sup
plementary notes assembled at the end of the book. These notes hence
contain material essential to a full understanding of the bearing of certain
of the evidence presented. The 1I0tes also contain references and lopical
reference lists, which have beel! made as comprehensive as was practi
cable, although they make no pretense to exhaustiveness. References are
to author and year only, the places of publication being obtainable, if de
l'Iired, from the General Bibliography.
OCCLUSION AND THE OCCLUDING METALS 3
anomalous in belonging to both subclasses, absorbing endothermically or
exothermically according to the temperature. So far as yet appears such
anomalies are found only in groups 6 and 1. '
II Nondifiusive occlusion during electrodeposition, sputtering, or the like
has seemingly no relation to the foregoing divisions but is shown by
OCCLUSION AND THE OCCLUDING METALS
metals of both the" B" and the" C" classes.
2.0 The commonest types of occlusion are diffusive processes in which The endothermic occluders, typified by iron and platinum, take up hy
hydrogen is taken up directly from the gas or is absorbed when liberated drogen only in small or moderate quantities, even at elevated tempera~
upon the metal either electrolytically or by chemical displacement. When tures, where their solubilities are greatest, in accordance with the positive
hydrogen is taken into the structure of metals, however, as these are in temperature coefficients, which necessarily accompany their negative
course of deposition, the product is still wholly metallic in character, and heats of absorption. Their hydrogen alloys- the products of occlusion
the process of its formation must be termed "occlusion/' in the sense of our are also of very simple constitution, displaying only one solid phase. This
definition. Such nondiffusive or congenital occlusion is displayed not only has commonly been regarded as a terminal solid solution of hydrogen in
by metals capable of the preceding type but by such as zinc or tin, which metal; but it is at present open to question whether solid solutions occur
are entirely impervious at ordinary or somewhat elevated temperatures, at all in endothermic metal-hydrogen systems.
when once their lattices have been iormed. Nondi.lfusive occlusion is con The exothermic occluders, of which palladium and tantalum are the
sidered in connection with electrodeposition (6.1) and with the deposition ~t-studied examples, absorb hydrogen in much larger quantities, form~
of metals in thin films, by evaporation, or by sputtering. Otherwise, the mg alloys of greater complexity, which exhibit unmistakable solid solu
following discussions are concerned only with absorption of the diffusive tions and one or more secolldary phases. These metals have sometimes
type, and it is to this that the tenn "occlusion" should be understood to been called "hydride-formers," a term for which the probable justifica
apply, whenever unqualified. tion will be discussed in chapter xiii.
2.1 In regard to their behavior toward hydrogen, the solid metals fall The anomalous manganese is intermediate in occlusive capacity be
into three classes, as may most readily be seen from the eighteen-group ar tween the two classes but, curiously enough, shows its greatest occlusions
rangement of the elements shown in our Table I. in the range in which absorption is endothermic.
The metals of the first, or" A/' class, included in groups 1 and 2, form With regard to certain metals and most alloys, our information as to
hydrides of saline character. The members of the second, or "E," class, occlusive behavior is still very inadequate or wholly lacking.
consisting of the elements of the twelfth and later groups, yield gaseous ~,2 Except for minor details which are here unimportant, Table I,
compounds analogous to the hydrocarbons and typified by the familiar which serves as the basis of our classification, is the now not uncom
arsine. The metals of the third, or" C," class, made up of the central ele mon eighteen-group periodic arrangement, selected because it differen
ments of groups 3-11 and including the rare-earth metals, either are inert tiates sharply the classes of metals which are unlike in occlusive behavior.
or else exhibit diffusive occlusion of the types named in the preceding The metals which we have termed "B metals" have long been so called,
section (on classification see 2.1.a). by reason of their position in the original table of Mendeleev. The term
Difiusive occlusion is thus confined to certain of the central elements, "A metal" is here adopted for convenience to designate the alkali and
"e
which, however, divide further into two subclasses: (1) the endothennic alkaline-earth elements, while the name metal" is given to the metals
occ1uders and (2) the exothermic occluders. Of these, the endothermic oc of the ce~t.ral block, which, save for a possible exception in group 11, are
c\uders embrace the occluding metals of groups 6-13, palladium alone the transltlOnal elements of current atomic theory.
e.""cepted, while the exothermic occ1uders consist of all the (investigated) Although the products of occlusion, the hydrogen alloys of the "C"
occluding metals found in groups 3-5 and among the rare earths and of metals resemble the hydrides of the" A" metals in showing variable com
some in groups 6-1, toge~er with palladium, isolated in group to. Man positions (Ephraim and Michel, 1921.I.II), the anaJogy appears to extend
ganese, probably with chromium and just possibly with molybdenum, is no further, since the hydrogen alloys form with expansion or without
1