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Copyright © 2013 by American Scientific Publishers
All rights reserved.
Printed in the United States of America
Journal of Advanced Physics
Vol. 2, pp. 1–5, 2013
(www.aspbs.com/jap)
Ultrasonic Damages in Iron
Filippo Ridolfi1, ∗, Fabio Cardone2,3 , and Gianni Albertini4
1Dipartimento di Scienze della Terra, della Vita e dell’Ambiente (DISTEVA), Università degli Studi di Urbino “Carlo Bo”,
Campus Scientifico “Enrico Mattei” Via Cà Le Suore 2, 61029 Urbino, Italy
2Istituto per lo Studio dei Materiali Nanostrutturati (ISMN–CNR), Via dei Taurini, 00185 Roma, Italy
3GNFM, Istituto Nazionale di Alta Matematica “F.Severi”, Città Universitaria, P.le A.Moro 2, 00185 Roma, Italy
4Dipartimento di Scienze e Ingegneria della Materia dell’Ambiente ed Urbanistica (SIMAU) Università’ Politecnica delle
Marche (UNIVPM), Via Brecce Bianche, 60131 Ancona, Italy
This work focuses on the characterization of the damage to a ferrite bar after exposure to ultrasounds. In par-
ticular, one of several damage zones on the surface of the bar is investigated through optic microscopes and
ESEM. This damage zone is roughly circular in shape, blackish in color and have a maximum dimension of
∼1 mm. On a microscopic scale the damage zone has a cratered morphology consisting of cracked material
with mass inferior to that of ferrite. The ∼20 m deep craters can be traced to local microexplosions caused
by sub-surface reactions that have resulted in partial fusion of the ferrite, and a rapid cooling and vetrification
of the fused material. In addition, a zone with a high density of deformed microcavities with irregular walls and
maximum dimensions of 10 m have been observed inside the bar. The microcavities are partially filled with
chaotic material lacking a clear shape. Preliminary EDS microanalyses of the amorphous cratered material of
the damage zone have produced spectra showing several elements apparently foreign to the ferrite whereas the
chaotic masses of the microcavities are characterized by an anomalous enrichment in carbon. These results
are important because the damages were produced by ultrasounds which also caused the emission of neu-
tron bursts. This appears consistent with a recently proposed theory predicting the occurrence of piezonuclear
reactions following the sudden collapse of intercrystalline cavities.
KEYWORDS: Ultrasounds, Damage, Cavity, Iron, Microexplosion, Piezonuclear Reaction.
1. INTRODUCTION
In recent experiments it has been found that materials with
high iron contents show evidence of damage after treat-
ment with 20 kHz ultrasounds.12In fact, the application
of longitudinal ultrasonic waves that are parallel but of
opposite directions to cylindrical bars made of steel and
alpha-iron (ferrite) has resulted in the emission of neu-
tron bursts and produced several roughly circular dark
regions on the bar surfaces with diameters of a few mm.
Preliminary semi-quantitative microanalyses of one of the
damage spots on a steel bar has shown the occurrence
of elements lighter than iron, apparently foreign to the
undamaged surface.2
Guided by their experience applying ultrasounds to
aqueous solutions3–7 and by theoretical analysis that pre-
dicts the deformation of spacetime due to pressure and the
cavitation phenomenon,8–10 Cardone et al.2have concluded
that the damages on the surfaces of the steel and ferrite
∗Author to whom correspondence should be addressed.
Email: filippo.ridolfi@uniurb.it
Received: 16 November 2012
Accepted: 25 January 2013
bars are the result of local piezonuclear reactions triggered
by the sudden collapse of intercrystalline cavities under
the influence of high pressures produced by the ultrasonic
waves.
Doubts on the possibility of nuclear reactions being
triggered by pressure alone and claims about the incom-
plete nature of the presented data, mistakes in the neu-
tron analysis due to intense acoustic background noise dur-
ing experiments and/or a presumably ignored trivial effect
that might be responsible for the reported experimental
results are reported.11–14 However, the latest experiments
on steel and ferrite alloys conducted by Cardone et al.2
leave little room for doubts about the existence of a hereto
unknown phenomenon, triggered by ultrasounds that merits
further research and attention from the scientific commu-
nity. In particular, these ultrasonic experiments on steel and
iron bars have shown, in addition to the emission of neutron
pulses which are difficult but not impossible to detect, tan-
gible evidence of reactions producing millimeter-size dam-
age zones on the cylindrical bar surfaces that are difficult
to explain with traditional theoretical principles.
In this work, optic and scanning electron microscopy
were used to investigate one of these damaged regions on
J. Adv. Phys. 2013, Vol. 2, No. 1 2168-1996/2013/2/001/005 doi:10.1166/jap.2013.1045 1
Ultrasonic Damages in Iron Ridolfi et al.
ARTICLE
the surface of a ferrite bar and to compare it with the
apparently intact surface regions. These techniques were
also used to investigate the interior of the ultrasonically
treated bar of ferrite.
2. SAMPLE PREPARATION AND
ANALYTICAL METHODS
One of the bars damaged by ultrasounds in the experiments
reported by Cardone et al.2has been analysed to charac-
terize the structural damages induced by ultrasounds.
This bar was a 10 cm long ferrite cylinder with a diam-
eter of 2 cm (Fig. 1). The bar was treated with 20 kHz
ultrasounds in 2009 at the laboratories of Startec Ltd using
the ultrasonic machine R-1-S, assembled and patented by
Startec Ltd.1215 It has been furnished by one of the
authors (FC) and was independently analysed in 2011 and
2012 at the laboratories of the “Università di Urbino” and
of the “Università Politecnica delle Marche”.
Sample preparation consisted in the extraction of two
parallelepipeds from the ferrite bar using a wire-EDM
(Electric Discharge Machining) belonging to Startec Ltd.
The wire cuts were performed perpendicular to the exter-
nal curved surface of the bar. The long dimensions of the
parallelepipeds correspond to the bar diameter (20 mm;
see Fig. 1) and the square, curved bases have a surface of
∼4mm
2. The square base of the first parallelepiped con-
tains one of the damaged dark areas (Fig. 2(a)), whereas
the second sample was extracted in correspondence with
an intact zone of the bar surface.
A first series of analyses of these square bases of the two
parallelepipeds which represent the external curved surface
of the bar, were performed by using optic microscopes
2 cm
damaged
area sample
reference
sample
ferrite bar
10 cm
Fig. 1. Sketch showing the dimensions of the bar and the location of
the extracted samples.
(a) (b)
(c) (d)
damage mark
oxidized
patch
damage mark
oxidized
patch
cavity
cavity
crater
Fig. 2. Microphotograph (a) and BSE images (b)–(d) of the paral-
lelepiped with the damage mark. (a) and (b) also show an oxidized patch
next to the damage mark. The BSE images in (c) and (d) show the close
up and cross-sectional view of the damage mark, respectively. In (d) the
occurrence of small cavities is also shown.
and an Environmental Scanning Electron Microscope
(ESEM).
After these analyses the samples were prepared for the
investigation of the internal zones of the bar. One of the
long faces of each of the parallelepipeds was polished
using sand paper and diamond paste of various grit sizes
(9, 6, 3, 1 m). A cross sectional view of the external
damage, was also obtained by polishing the sample down
to the centre of the external damage mark. The polished
surfaces were quickly (≤10 sec) cleaned with water and
90% ethyl alcohol and dried using compressed air immedi-
ately after each cleaning. To avoid oxidation, the samples
were placed into a desiccator where they remained until a
few hours before the microscope and ESEM analyses of
the internal zones of the bar.
The optic microscope observations were mostly used
for a preliminary characterization of the samples. The
employed microscopes use non-polarized and polarized
reflected light. The ESEM analyses were performed with
a FEI Quanta 200 which is equipped with a field emis-
sion gun, detectors for secondary electron (SE) and back
scattered electron (BSE) imaging, and an EDS (Energy
Dispersive System) for X-ray atomic analysis.
The ESEM operational conditions were: vacuum of
5.0 ·10−6mbar; accelerating voltage of 30 kV; beam cur-
rent of 264 mA. All the early in situ X-ray analyses
were performed with a counting time of 100 sec and
maintaining a working distance of 9.7 mm. This setting
allows to identify almost all the natural elements of the
periodic table (from B to U) and accounts for maxi-
mum SE and BSE image resolutions of 3.0 and 4.0 nm,
respectively.
2J. Adv. Phys., 2, 1–5, 2013
Ridolfi et al. Ultrasonic Damages in Iron
ARTICLE
3. RESULTS
Microscope and ESEM observations allowed us to obtain
microstructural data on the external damages and internal
zones of the ferrite bar (Figs. 2, 3). The damage marks on
the ferrite surface are smaller (maximum size of ∼1 mm)
than the 2–3 mm large, roughly circular spots produced by
ultrasounds on the steel bars.2They are mostly irregular
in shape and are well distinguishable from oxidized (rust)
patches and the drawn, intact surface of the ferrite bar in
having a predominantly black colour (Fig. 2(a)). It is worth
noting that the rust patches were not present at the time of
the ultrasounds treatment (2009) and are most likely the
result of natural oxidation of the iron on the ferrite surface
between 2009 and 2011.
BSE imaging of the damage mark showed a cratered
surface of lower brightness (i.e. low mean atomic weight)
with respect to the intact ferrite surface (Fig. 2(b)). Bright
remnants of the original ferrite surface can also be found
in between the cratered zones, which are characterized by
irregular and cracked interiors composed of a material with
a lower mass (i.e., dark) (Fig. 2(c)). The cross-sectional
view of the damage mark suggests that the thickness of the
low-brightness material is minimal, possibly ≤1 micron
(Fig. 2(d)). The deeper craters have depths of about 20 m
and indicate highly energetic microexplosions.
Figure 2(d) also shows some small cavities found inside
the bar at about 30–50 m from the damage mark and
the craters. A zone with a large number of cavities can
also be observed between ∼0.3 and ∼1.3 mm from the
external damage mark. In this zone the density of cav-
ities is about 500 per mm2(Fig. 3(a)). The largest of
these cavities has a size of ∼10 m. At higher magnifi-
cations the cavities appear highly deformed with irregular
(a) (b)
(c) (d)
50 µm
Fig. 3. Microscope polarized light (a) and SE images (b)–(d) showing
the density and microstructure of the cavities inside the bar. (d) is a close
up of the cavity interior in (c).
contours (Figs. 3(b), (c)) and are partially filled with mate-
rial (Fig. 3(d)). This material is chaotic and amorphous
in appearance but we can safely discard the hypothesis
that it is the remnant of the oil-based diamond pastes used
in sample preparation as it did not show any diamond
grains or the typical blurring of fat materials during SE
observations.
It is worth noting that none of these structural features
were found on either the external surface or in the interiors
of the reference parallelepiped, which occasionally shows
empty cavities of smaller sizes (<5m). Some typical
Fe–C alloy inclusions [see Ref. [16]] found in both sam-
ples are Mg and Ca spinels and oldhamite, a CaS phase
with minor Mn, Mg and C contents. These phases are not
abundant and do not show evidence of any type of reac-
tions. They are usually found as small (sizes ≤2m)
sub-euhedral inclusions in the ferrite matrix. One elongate
and irregular cavity (maximum dimension ∼15 m) in the
sample with the damage mark was found hosting several
small crystals of Mg–Ca spinel.
Preliminary EDS analyses of the ferrite matrix and the
anomalous structural features found in the parallelepipeds
were also performed. Figure 4 shows the reference spec-
trum of the homogeneous intact ferrite whereas in Figure 5
two representative X-ray spectra of materials from the
external damage mark and those of the cavities inside the
bar are reported. The ferrite matrix is, as expected, com-
posed of iron with minor amounts of carbon, chromium
and manganese. The intact ferrite spectrum also shows two
artifact peaks, a consequence of the high Fe count rate,
with energies comparable to the Si K1,2 peak and the La
L1,2 peak.
These peaks, as well as those characteristic of Fe, C, Cr
and Mn, can also be found in the spectra of the materi-
als from the external damaged zone and inside the micro-
cavities in the bar’s interior. In addition, spectra of the
damage mark (e.g., Fig. 2(c)) show peaks of elements not
present in the intact ferrite such as oxygen, sodium, alu-
minum, sulfur, chlorite, potassium, calcium and copper,
as well as a more pronounced carbon peak (e.g., Fig. 5).
This enrichment in carbon is particularly evident in the
intact ferrite
matrix
Fe
Fe
Fe
C Cr Mn
Fe
(artifact)
Fe
(artifact)
Fig. 4. Qualitative EDS spectrum of the pollished surface of the refer-
ence ferrite parallelepiped.
J. Adv. Phys., 2, 1–5, 2013 3
Ultrasonic Damages in Iron Ridolfi et al.
ARTICLE
surface damage
Fe
Fe
Fe
CSi + artifact of Fe
Cr Mn
Fe
(artifact)
Cu
Cu
Na
Al
O
S
Cl
KCa
internal cavity
Si + artifact of Fe
C Fe
Fe
O00
Fe
S
Fe
(artifact)
Cr Mn
Al?
Ca?
Fig. 5. Qualitative EDS spectra of the materials of the surface damage
mark and in a cavity inside the ferrite bar. The two spectra were obtained
at the same operating conditions and have the same vertical counting
scale.
spectra obtained during the analyses of the formless mate-
rial filling the microcavities (Fig. 3(c),(d)), which is also
characterized by lower amounts of oxygen and sulfur with
respect to the damaged mark (Fig. 5). The presence of any
other elements within the cavity fill material that is not
found in the intact ferrite cannot be detected by ESEM-
EDS analysis.
4. DISCUSSION
Cardone et al.2suggested that the neutron bursts emitted
by the steel and ferrite bars during the ultrasound treat-
ment are either due to so-called “piezonuclear reactions”
induced by a local spacetime deformation generated by
sufficient local energy density or due to a release of energy
which increases the temperature determining the condi-
tions of microplasma ignition. Both hypotheses are consis-
tent with the occurrence of microcavities in the bars which,
unlike the ferrite matrix, are unable to promptly release
the energy received from the ultrasound waves. The large
number of highly deformed cavities at a depth of just a
few millimeters inside the sample containing the damage
mark (Fig. 3) strongly supports the piezonuclear hypoth-
esis. In fact, their maximum size (∼10 m) is consistent
with the theoretical calculations of the spacetime defor-
mation induced by cavitation.8–10 In accordance with these
calculations and to protect the technicians of Startec Ltd
from any unexpected and/or uncontrollable side-effects,
it was chosen to work at a relatively low power (19 W)
which would still be sufficiently high to transfer over
370 GeV of energy through the bar to the internal cavi-
ties guaranteeing their collapse and the triggering of the
subsequent piezonuclear reactions.2
The structural characteristics of the damage mark and
the material composing it (Fig. 2) suggest that they are
the result of violent reactions within sub-surface zones that
have led to the partial fusion of the ferrite and the sud-
den fracturing and expulsion of the superficial layers of
the bar. This is supported by the presence of bright rem-
nants of pristine ferrite surface in between the cratered
dark material (Fig. 2(c)) and the limited depth (∼20 m)
of the craters (Fig. 2(d)). In addition, the cracking demon-
strated by the cratered material (Fig. 2(c)) and the pres-
ence of higher quantities of oxygen with respect to the
internal cavities (Fig. 5) suggest that the Fe-rich melt gen-
erated by the reaction has interacted with the surrounding
atmosphere cooling briskly following the microexplosion.
Furthermore, parts of the fused material were most likely
expulsed during the explosive phase as suggested by its
minimal thickness in cross-sectional view (Fig. 2(d)). This
is in agreement with the presence of the characteristic fer-
rite peaks (i.e., those of Fe, Cr, Mn) in the EDS spectra
of the damage mark material (Fig. 5) which suggest that
the ESEM electron beam had gone through the thin crust
of amorphous material and was interacting primarily with
the ferrite matrix (see Fig. 4 for reference spectrum).
The presence within the material of elements lighter
than iron may be due to
(i) piezonuclear reactions which determined the scission
of iron,2
(ii) the presence of mineral inclusions within the cavities
that have melted and mixed with the reaction generated
liquid and
(iii) the presence of impurities on the bar surface intro-
duced during the fabrication process (wire drawing).
However, the presence of an element heavier than Fe (i.e.,
copper; Fig. 5) that is apparently foreign to the ferrite
matrix, to its inclusions and to the dies generally used in
bar manufacturing, is puzzling and may favor the occur-
rence of nuclear reactions.
The same piezonuclear phenomenon is likely to have
also occurred within the deformed microcavities in the bar
interior (Fig. 3). The irregular morphology of the material
inside the microcavities (Figs. 3(c),(d)) cannot be due to
the low resolution of the ESEM but rather to the actual
characteristics of the material itself since at the operating
conditions used, the FEI Quanta 200 instrument is capa-
ble of distinguishing objects with dimensions as little as
3 nm. It is therefore likely that the material inside the cav-
ities is composed of a chaotic assemblage of sub-micron
sized particles, most likely amorphous, formed as a result
4J. Adv. Phys., 2, 1–5, 2013
Ridolfi et al. Ultrasonic Damages in Iron
ARTICLE
of the liberation of energy in a closed system, i.e., in the
intercrystalline cavities confined within the ferrite matrix.
The EDS spectra of the material in the microcavities (e.g.,
Fig. 5) are inferred to be a product of the summation of
X-rays originating from the materials within the micro-
cavities (to a small degree) and those of the surrounding
ferrite matrix (to a large degree) just as for the damage
mark. Nevertheless, the spectra suggest that the material
is predominantly composed of carbon (Fig. 5) that may
derive from either the scission of iron nuclei2or from the
remobilization of the primary elemental constituents of the
ferrite matrix.
5. CONCLUDING REMARKS
The results presented are in no way conclusive but are
in agreement with the theoretical approaches and with the
experimental results of previous studies about piezonu-
clear phenomenon1–10 which in our eyes provide a possible
explanation for the observed phenomenon. Our attempts to
hypothesize a variety of other processes that could have
produced the observed damages have been of little suc-
cess. For example, assuming that the detected neutrons2
are the result of measurement errors or of the occur-
rence of some unknown, undesired phenomenon during
measurement,11–14 the external damage marks could be
the result of the combustion of sulfur minerals commonly
found in Fe–C alloys, such as the CaS inclusions present
in the analyzed bar. However, these inclusions have not
been found to be in contact with the air (and therefore
the oxygen) trapped within the cavities but rather as occa-
sional single inclusions completely filling the intercrys-
talline spaces of the ferrite. This should be enough to
exclude the possibility of some of them undergoing com-
bustion. In addition, a similar combustion process should
have left calcium- and sulfur-rich residues, while of all the
elements foreign to the ferrite the Ca and S peaks in
the EDS spectra of the damage mark material are among
the lowest. Also, the S, Ca and O detected within the
microcavities appear irrelevant (Fig. 5).
In conclusion, the observations reported in this work
lend support to the occurrence of piezonuclear reactions
but does not demonstrate that such reactions are capable
of producing new elements. Most likely this could only be
demonstrated with absolute certainty by performing iso-
topic microanalyses of the materials produced in these
reactions.
An in depth semi-quantitative ESEM-EDS analysis will
be the focus of a forthcoming article which will try to
answer questions such as:
(I) Why are the amounts of the structural damages and
chemical changes at the bar surface greater than inside the
bar?
(II) Why does the carbon content in the microcavities
inside the bar appear higher than in the blackish material
of the damaged surface?
(III) Are these differences the result of more than one
reaction mechanism operating within in the same bar?
(IV) What is the hypothetical role of the impurities and
inclusions during the reactions inside and at the surface of
the ferrite bar subjected to ultrasounds?
Acknowledgments: We would like to thank G. Fattorini
and A. Rotili for helpful discussions and for their support.
Special thanks are due to W. Sala, administrator of the
Startec Ltd, for supplying the ferrite bar.
References and Notes
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transmutations, Iron–Proceedings of ICCF-16 International Con-
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WO/2008/041254.
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WO/2008/041255.
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J. Adv. Phys., 2, 1–5, 2013 5
