Fe Zr Research Articles

Microstructure, mechanical and anti-corrosion property evaluation of iron-based thin film metallic glasses

Thin film metallic glasses (TFMGs) represent a class of promising engineering materials for structural applications. Despite the effort that has been made in the development of TFMG materials, the iron-based thin film metallic glasses fabricated by sputtering have gained limited attention. In this work, five iron-based Fe–Zr–Ti thin film metallic glasses with different Fe contents ranging from 37.6 to 49.8at.% were prepared by magnetron co-sputtering system using pure Fe, Zr and Ti targets. Through XRD and TEM analyses, the amorphous phase was confirmed for each coating. The glass transition temperature (Tg) and crystallization temperature (Tx) of TFMG increased with increasing Fe content and reached 963K and 989K, respectively, when Fe content was 49.8at.%. The supercooled liquid region was around 26.3 to 51.6°C, which was shown to be unrelated to Fe concentration. The hardness, elastic modulus, and H/E ratio of TFMGs increased with increasing Fe concentration. Based on the HRC-DB test, adequate adhesion quality was obtained for all TFMGs. The corrosion resistance of TFMGs also increased with increasing Fe content and spontaneous passivation behavior was discovered due to the large content of Zr and Ti valve metals. Nevertheless, the corrosion resistance of Fe–Zr–Ti TFMGs was strongly influenced by surface defects. A series of high hardness Fe–Zr–Ti thin film metallic glasses with good adhesion property and adequate corrosion resistance was reported in this study.

Characterization of solidified melt among materials of UO2 fuel and B4C control blade

To predict the fundamental phase relationships in the solidified core melt of the Fukushima Daiichi Nuclear Power Plant, solidified melt samples of the various core materials [B4C, stainless steel, Zr, ZrO2, (U,Zr)O2] were prepared by arc melting. Phases and compositions in the samples were determined by means of X-ray diffraction, microscopy, and elemental analysis. With various compositions, the only oxide phase formed was (U,Zr)O2. After annealing, the stable metallic phases were an Fe-Cr-Ni alloy and an Fe2Zr-type (Fe,Cr,Ni)2(Zr,U) intermetallic compound. The borides, ZrB2 and Fe2B-type (Fe,Cr,Ni)2B, were solidified in the metallic part. Annealing at 1773 K under an oxidizing atmosphere (Ar-0.1%O2) resulted in the oxidation of U and Zr in the alloy and in ZrB2, and consequently the (Fe,Cr,Ni)2B and Fe-Cr-Ni alloy became dominant in the metallic part. The experimental phase relationships in the metallic part agreed reasonably with the thermodynamic evaluation of equilibrium phases in a simplified B4C–Fe–Zr system. The metallic Zr content in the melt was found to be a key factor in determining the phase relationships. As a basic mechanical property, the microhardness of each phase was measured. The borides, especially ZrB2, showed notably higher hardness than any other oxide or metallic phases.

Diffusional Interaction Between U-10 wt pct Zr and Fe at 903 K, 923 K, and 953 K (630 °C, 650 °C, and 680 °C)

U-Zr metallic fuels cladded in Fe-alloys are being considered for application in an advanced sodium-cooled fast reactor that can recycle the U-Zr fuels and minimize the long-lived actinide waste. To understand the complex fuel-cladding chemical interaction between the U-Zr metallic fuels with Fe-alloys, a systematic multicomponent diffusion study was carried out using solid-to-solid diffusion couples. The U-10 wt pct Zr vs pure Fe diffusion couples were assembled and annealed at temperatures, 903 K, 923 K, and 953 K (630 °C, 650 °C, and 680 °C) for 96 hours. Development of microstructure, phase constituents, and compositions developed during the thermal anneals were examined by scanning electron microscopy, transmission electron microscopy, and X-ray energy dispersive spectroscopy. Complex microstructure consisting of several layers that include phases such as U6Fe, UFe2, ZrFe2, α-U, β-U, Zr-precipitates, χ, e, and λ were observed. Multi-phase layers were grouped based on phase constituents and microstructure, and the layer thicknesses were measured to calculate the growth constant and activation energy. The local average compositions through the interaction layer were systematically determined, and employed to construct semi-quantitative diffusion paths on isothermal U-Zr-Fe ternary phase diagrams at respective temperatures. The diffusion paths were examined to qualitatively estimate the diffusional behavior of individual components and their interactions. Furthermore, selected area electron diffraction analyses were carried out to determine, for the first time, the exact crystal structure and composition of χ, e, and λ-phases. The χ, e, and λ-phases were identified as Pnma(62) Fe(Zr,U), I4/mcm(140) Fe(Zr,U)2, and P42/mnm(136) U3(Zr,Fe), respectively.

Influence of noble metal fission products and uranium on the microstructure and corrosion behaviour of D9 stainless steel–zirconium metal waste form alloy

Metal waste form (MWF) alloys of composition D9SS–8.5Zr, D9SS–10Zr–1NMFP and D9SS–10Zr–1NMFP–10U were prepared by casting of D9SS (Ti-modified austenitic 316 stainless steel), zirconium, NMFPs (noble metal fission products) and uranium for evaluating the influence of NMFPs and U on the microstructure and corrosion resistance of MWF alloys. Gradual increase in the hardness value was observed with the addition of NMFPs and uranium. Microstructural characterisation revealed the formation of Zr-rich intermetallic phases in these alloys which act as hosts for NMFPs and U. Fe–Zr and Ni–Zr based intermetallics were identified in D9SS–Zr and D9SS–Zr–NMFP alloys by XRD technique. In the U added alloy, UZrO2 and NiU2 were observed along with Fe–Zr and Ni–Zr intermetallics. Electrochemical corrosion monitoring confirmed active corrosion potential and higher passive current density with the addition of NMFPs and U. The MWF alloy with NMFPs showed higher break down potential with high polarization resistance revealing stable passive film.

Material Tailoring of Ti–V–Fe–Zr for Improving Sorption Behaviour Employing Off Stoichiometric Concentration of Native Element Ti

Material Tailoring of Ti–V–Fe–Zr for Improving Sorption Behaviour Employing Off Stoichiometric Concentration of Native Element Ti

High-throughput ab initio screening of binary solid solutions in olivine phosphates for Li-ion battery cathodes

A promising approach to improving the performance of iron-phosphate FePO4 cathode materials for Li-ion batteries is to partly or fully substitute Fe with other metals. Here, we use high-throughput density-functional theory (DFT) calculations to investigate binary mixtures of metal atoms M and M′ in (Li)MyM′1−yPO4 olivine phosphates. We determine the formation energy for various stoichiometries of different binary combinations of metals for the cases of full lithiation and delithiation. Systematic screening of all combinations of Fe and Mn with elements of the 3d transition-metal (TM) series allows us to identify trends with average band filling and atomic size. We also included compounds that verify the observed relations or that were discussed as cathode materials, particularly Ni–Co, V–Cu and V–Ni, as well as combinations with 4d TMs (Fe–Zr, Fe–Mo, Fe–Ag) and with Mg (Fe–Mg and Ni–Mg). Based on our DFT calculations for each compound, we estimate the volume change during intercalation, the intercalation voltage, the energy density and the thermal stability with respect to reaction with oxygen. Our calculations indicate that the energy density of the binary TM phosphates increases with average band filling while the thermal stability of the compounds decreases.

Changes in electronic, magnetic and bonding properties from Zr2FeH5 to Zr3FeH7 addressed from ab initio

Potential hydrogen storage ternaries Zr3FeH7 and Zr2FeH5, are studied from ab initio with the purpose of identifying changes in electronic structures and bonding properties. Cohesive energy trends: Ecoh. (ZrH2) > Ecoh. (Zr2FeH5) > Ecoh. (Zr3FeH7) > Ecoh. (hypothetic-FeH) indicate a progressive destabilization of the binary hydride ZrH2 through adjoined Fe so that Zr3FeH7 is found less cohesive than Zr2FeH5. From the energy volume equations of states EOS the volume increase upon hydriding the intermetallics leads to higher bulk moduli B0 explained by the Zr/Fe–H bonding. Fe–H bond in Zr2FeH5 leads to annihilate magnetic polarization on Fe whereas Fe magnetic moment develops in Zr3FeH7 identified as ferromagnetic in the ground state. These differences in magnetic behaviors are due to the weakly ferromagnetic Fe largely affected by lattice environment, as opposed to strongly ferromagnetic Co. Hydrogenation of the binary intermetallics weakens the inter-metal bonding and favors the metal–hydrogen bonds leading to more cohesive hydrides as with respect to the pristine binaries. Charge analyses point to covalent like Fe versus ionic Zr and hydrogen charges ranging from covalent H−0.27 to more ionic H−0.5.

Transmission electron microscopy study of the microstructure of a Ti–Fe–Zr alloy

A Ti–35Fe–30Zr (at.%) alloy was prepared by cold crucible levitation melting, and its microstructure was characterized. Electron microscope observations revealed a microstructure with a bi-modal phase size distribution. One phase was identified as a monoclinic TiFeZr compound with lattice parameters a=0.895nm, b=0.502nm, c=0.969nm, and α=119.4° in C2 (space group). A bcc β-TiZr phase with lattice parameter a=0.341nm coexisted with the monoclinic phase. The mechanisms of phase formation are discussed.

Thermodynamic modeling and experimental study of the Fe–Cr–Zr system

This work developed thermodynamic models for describing phase stability and thermodynamic property of the Fe–Cr–Zr system using the Calphad approach coupled with experimental study. Thermodynamic descriptions of the Fe–Cr and Cr–Zr systems were either directly adopted or slightly modified from literature. The Fe–Zr system has been remodeled to accommodate recent ab-initio calculation of formation enthalpies of various Fe–Zr compounds. Reliable ternary experimental data and thermodynamic models were mainly available in the Zr-rich region. Therefore, selected ternary alloys located in the vicinity of the eutectic valley of β(Fe,Cr,Zr) and (Fe,Cr)2Zr laves phase in the Fe-rich region have been experimentally investigated in this study. Microstructure has been examined by using scanning electron microscope, energy-dispersive X-ray spectroscopy and X-ray diffraction. These experimental results, along with the literature data were then used to develop thermodynamic models for phases in the Fe–Cr–Zr system. Calculated phase equilibria and thermodynamic properties of the ternary system yield satisfactory agreements with available experimental data.

A new thermodynamic parameter to predict glass forming ability in iron based multi-component systems containing zirconium

A new thermodynamic parameter PHSS (PHSS = ΔHC(ΔSσ/kB)(ΔSC/R)) is proposed, to describe and predict the glass forming ability (GFA) of Fe based alloys. Here ΔHC is the chemical enthalpy of mixing, ΔSσ is the mismatch entropy and ΔSC is the configurational entropy. The PHSS parameter incorporates enthalpy of mixing, size mismatch and the number of elements in the systems which influence GFA significantly. It was observed from rapid solidification processing (RSP) and mechanical alloying (MA) studies that, all alloys with PHSS in between −0.55 kJ/mol to −6.00 kJ/mol would form glass in the Fe–Zr–B system. MA and RSP experiments on multi-component Fe–Cr–Ni–Zr–B alloys indicated that PHSS is a better parameter to predict GFA of the system than PHS, a parameter used in earlier studies. It was also observed that bulk metallic glass (BMG) forming alloys can be observed in between a PHSS range of −3.00 kJ/mol to −6.00 kJ/mol, with the maximum thickness of the BMG increasing with decreasing PHSS within the above range.

The Mitochondria Free Iron Content to Limit an Isotope Effect of 25Mg2+ in ATP Synthesis: A caution

Sir: The Mg-promoted magnetic isotope effect (MIE), that is a nuclear spin selective over-activation of mitochondrial ATP synthesis by Mg nuclei, has been first discovered and originally described in a pioneer work by Buchachenko et al. [1] published in Cell Biochem. Biophys. back in 2005. Since then, a number of subsequent studies were uncovering some details of its ion–radical mechanism [2–5] with emphasize on potential medicinal applications due to both in vitro and in vivo experiments [6–9]. Obviously, a nuclear–magnetic control over the metal dependent enzymatic catalysis might be affected by traces of any other than Mg magnetic (paramagnetic, ferromagnetic) bivalent cations. In general, a possibility of the nucleotide phosphorylation dysfunctions caused by changes in intra-mitochondrial free metal cations pool was in fact ‘‘stated for alert’’ long ago [10]. As per the role of iron as a powerful suppressor for Mg-MIE in the nucleotidyl kinases directed ATP formation, this became clear just recently [5, 11]. Being attractive to pharmacologists [4, 6–8] and biotechnologists [12], Mg-MIE deserves to be specifically tested for its dependence on iron traces in situ. So we have investigated a correlation between the contents of free Fe in mitochondria isolated from several rat tissues (iron– lacking media employed), and the ATP synthesis rates estimated using these mitochondria in vitro respiration systems [13] in the presence of optimal (20 mM MgCl2) concentrations of either magnetic (Mg) or non-magnetic (Mg) ions [1, 3]. Both A grade isotopes with the enrichment level of not less than 96.4 % were purchased from Gamma Lab SA (Alicante, Spain). ATP synthesis rates were estimated by [p] orthophosphate (6.78–8.45 Ci/mmol, Amersham Radiochemical Centre, UK) incorporation in to de novo synthesized ATP [1] in the in vitro ‘‘breathing’’ mitochondria [13]. Mitochondria were isolated from the following rat tissues: spleen [14], liver [15], skeletal muscles [16], heart muscle [17], kidneys [18], and brain [19]. To get the intra– mitochondrial free iron pool samples, the pre-washed mitochondria pellets were first subjected to Triton X-100/ acetone treatment and then to a triple acetone–extraction of the total low molecular weight compounds fraction [1]. The resulting samples were used to measure the Fe content values by the energy–dispersive X-ray fluorescence spectrometry with a Fe–Zr performance element range employing the XEPOS–HE analytical system (SPECTRO Analytical Instruments, GmbH, Kleve, Germany). As seen from the data obtained (Table. 1), the endogenous mitochondrial-free iron pool level is no doubt critical for ‘‘turning on–off’’ the Mg-magnetic isotope effect expressing in a whole integrative (unbroken) mitochondria, i.e., within their ATP–synthesizing machinery. A. A. Svistunov Y. K. Napolov A. A. Bukhvostov (&) Department of Pharmacology, School of Pharmacy, I. M. Sechenov Moscow State Medical University, Moscow, Russia e-mail: tanzbukh@gmail.com

Development of new alginate entrapped Fe(III)–Zr(IV) binary mixed oxide for removal of fluoride from water bodies

The present work reports the decontamination of fluoride from water bodies using a newly developed hybrid material of (Fe/Zr)–alginate (FZCA) microparticles. The hybrid material was characterized by various instrumentation techniques. The average particle size of the Fe–Zr particle was found to vary between 70.89nm and 477.7nm. The XRD pattern of FZCA shows most significant peaks at 11.5, 35.3, 26.9, 39.4 and 56.1 in the 2θ range of 10–90°. Various physico-chemical parameters such as equilibrium contact time, pH, initial fluoride concentration and adsorbent dose, were studied in batch adsorption experiments. The sorption of fluoride follows pseudo-second order kinetics. The positive value of thermodynamic parameter (ΔHo) indicates increasing randomness during the sorption process. The desorption characteristic of the hybrid material shows that nearly 89% of fluoride could be leached out at pH 12. A possible mechanism of fluoride removal by the hybrid material was also purposed. Further, the reusable properties of the material support further development for commercial application purpose.

Prediction of Glass Forming Ability Using Thermodynamic Parameters

Formation of a glassy phase in metallic systems is controlled to large extent by the composition of the alloy. Alloying behavior can be qualitatively predicted from the knowledge of enthalpy of mixing and atomic size mismatch among elements involved in bonding. A more quantitative description of glass forming ability (GFA) can be obtained by using a parameter PHS [= ΔHC(ΔSσ/kB)], where ΔHC is the chemical enthalpy of mixing and ΔSσ/kB is entropy due to atomic size mismatch normalized by Boltzmann constant. Using this criterion, alloys with high GFA were identified in several ternary systems. However, PHS parameter was found to be insufficient to predict GFA in multicomponent systems. Present analysis indicates that the incorporation of configurational entropy into PHS parameter resulted in more quantitative description to explain higher GFA in multicomponent systems. This new GFA parameter is called PHSS (= PHS × ΔSC/R), where ΔSC/R is the configurational entropy normalized by universal gas constant. Using PHS and PHSS parameters, GFA predictions are done for Fe–Zr–B, Fe–Cr–Zr–B, Fe–Cr–Ni–Zr–B, Cu–Zr–Ag–Ti, Cu–Zr–Al–Y and Cu–Zr–Al–Be systems and an attempt has been made establish the suitability of this new GFA parameter to various quaternary and quinary alloy systems.

Understanding the phase equilibrium and irradiation effects in Fe–Zr diffusion couples

We have studied the radiation effects in Fe–Zr diffusion couples, formed by thermal annealing of a mechanically bonded binary system at 850°C for 15days. After irradiation with 3.5MeV Fe ions at 600°C, a cross sectional specimen was prepared by using a focused-ion-beam-based lift out technique and was characterized using scanning/transmission electron microscopy, selected-area diffraction and X-ray energy dispersive spectroscopy analyses. Comparison studies were performed in localized regions within and beyond the ion projected range and the following observations were obtained: (1) the interaction layer consists of FeZr3, FeZr2, Fe2Zr, and Fe23Zr6; (2) large Fe23Zr6 particles with smaller core particles of Zr-rich Fe2Zr are found within the α-Fe matrix; (3) Zr diffusion is significantly enhanced in the ion bombarded region, leading to the formation of an Fe–Zr compound; (4) grains located within the interaction layer are much smaller in the ion bombarded region and are associated with new crystal growth and nanocrystal formation; and (5) large α-Fe particles form on the surface of the Fe side, but the particles are limited to the region close to the interaction layer. These studies reveal the complexity of the interaction phase formation in an Fe–Zr binary system and the accelerated microstructural changes under irradiation.

Relevance of Fe atomic volumes for the magnetic properties of Fe-rich metallic glasses

The atomic volume Va-Fe that can be assigned to Fe atoms in Fe–metalloid (Fe–MD) and Fe–early transition metal (Fe–TE) glasses was deduced in a previous paper (I. Bakonyi, Acta Materialia 53 (2005) 2509) from an analysis of available density data for such amorphous alloys. In the present paper, based on a similarity of the amorphous and face-centered cubic (fcc) structures, the distinctly different magnetic behaviors of these two families of amorphous alloys are discussed in terms of the relative position of Va-Fe and the critical volume Vfcc⁎-Fe≈11.7Å3/atom separating the so-called low-spin (LS) and high-spin (HS) state of fcc-Fe. For Fe–MD systems, Va-Fe is found to be definitely larger than Vfcc*-Fe whereas for Fe-TE systems Va-Fe is fairly close to Vfcc*-Fe. Since in topologically disordered alloys a distribution of atomic volumes is inherently present, in Fe–MD glasses the Fe atoms can be assumed to exhibit exclusively the HS state whereas in Fe–TE amorphous alloys a comparable fraction of Fe atoms can be either in the LS or the HS state. According to previous theoretical band structure calculations, an antiferromagnetic state can also be stable just around Vfcc*-Fe. The simultaneous presence of Fe atoms with such a rich variety of magnetic states due to the specific position of the average of the atomic volume distribution can well explain the complex magnetic behavior observed in Fe-rich Fe–TE metallic glasses such as, e.g., in amorphous Fe–Zr alloys around 90at% Fe.

A thermokinetic description of nanoscale grain growth: Analysis of the activation energy effect

The inhibition of grain growth by solute segregation in nanoscale materials has often been described using kinetic models (e.g. Acta Mater 1999;47:2143) or thermokinetic models (e.g. Acta Mater 2009;57:1466), in which constant activation energy and a negligible effect of solute segregation on activation energy were assumed. In this paper, an intact thermokinetic model for nanoscale grain growth was developed by incorporating mixed effects of activation energy and grain boundary (GB) energy. By application of the model to nanoscale grain growth in Ni–P, Pb–Zr, Fe–Zr and Ru–Al alloys, the validity of the present model was confirmed, in combination with verification of the initial condition of GB segregation. On this basis, the increase of activation energy and the decrease of GB energy are interrelated and thus the kinetics and the thermodynamics of normal grain growth are linked. Based on a comparison of three characteristic velocities VTK, VGE and VAE of GB derived from the present thermokinetic model, grain boundary energy model and activation energy model, a mechanism of controlled nanoscale grain growth was proposed, which indicated a transition from a kinetic-controlled to a thermodynamic-controlled process.

Ion beam mixing study of the favored glass-forming region of the ternary Fe–Zr–Nb system

For the Fe–Zr–Nb system, ion beam mixing of multiple metal layers with various compositions was carried out. Using high resolution transmission electron microscopy analyses, nine compositions were determined to be favored for metallic glass formation. It is found that all these composition points fall in a hexagonal region defined by linearly connecting the six composition points determining the glass-forming ranges of its sub-binary systems. It is therefore proposed to predict the favored glass-forming region for a ternary metal system by the glass-forming ranges of its sub-binary systems.

High Temperature Phase Stability and Microstructural Characterization of D9 Stainless Steel-Zirconium Metal Waste Form Alloys

Zirconium present in stainless steel-zirconium metal waste form (MWF) alloys form Ni–Zr and Fe–Zr intermetallic phases which act as a sink for radionuclide and improve resistance to localized corrosion as well as selective radionuclide leaching. The present study looks into the behavior of Zr intermetallics in MWF alloys with the variation of Zr content after heat treatments. Two MWF alloys of D9 SS (Ti modified 15Cr–15Ni–2.5Mo stainless steel) with 8.5 and 17 wt% Zr were heat treated at 1,323 K for 2 and 5 h and characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The stability of the Zr intermetallic compounds was examined by high temperature XRD. The results from XRD study showed the presence of NiZr, Ni5Zr, Ni7Zr2, FeZr2, and Fe3Zr peaks along with fcc Fe based solid solution. The MWF alloy with 17 wt% Zr exhibited α-ferrite peak in as-cast condition which was not observed after heat treatment. From the SEM micrograph the agglomeration of intermetallic phases was observed after heat treatment and the grain size of the intermetallic phases increased with duration of heat treatment. The high temperature XRD study revealed that all the intermetallic phases were stable up to 1,173 K and above this temperature Ni–Zr intermetallics started disappearing. However Fe–Zr intermetallics were stable till 1,373 K. The paper presents the high temperature phase stability of D9 SS-Zr MWF alloys.

Adsorption of Phosphate from Aqueous Solution Using an Iron–Zirconium Binary Oxide Sorbent

In this study, an iron–zirconium binary oxide with a molar ratio of 4:1 was synthesized by a simple coprecipitation process for removal of phosphate from water. The effects of contact time, initial concentration of phosphate solution, temperature, pH of solution, and ionic strength on the efficiency of phosphate removal were investigated. The adsorption data fitted well to the Langmuir model with the maximum P adsorption capacity estimated of 24.9 mg P/g at pH 8.5 and 33.4 mg P/g at pH 5.5. The phosphate adsorption was pH dependent, decreasing with an increase in pH value. The presence of Cl−, SO 4 2− , and CO 3 2− had little adverse effect on phosphate removal. A desorbability of approximately 53 % was observed with 0.5 M NaOH, indicating a relatively strong bonding between the adsorbed PO 4 3− and the sorptive sites on the surface of the adsorbent. The phosphate uptake was mainly achieved through the replacement of surface hydroxyl groups by the phosphate species and formation of inner-sphere surface complexes at the water/oxide interface. Due to its relatively high adsorption capacity, high selectivity and low cost, this Fe–Zr binary oxide is a very promising candidate for the removal of phosphate ions from wastewater.

A COMBINED MULTI‐ANALYTICAL APPROACH FOR THE STUDY OF ROMAN GLASS FROM SOUTH‐WEST IBERIA: SYNCHROTRON μ‐XRF, EXTERNAL‐PIXE/PIGE AND BSEM–EDS

An integrated, multi‐analytical approach combining the high sensitivity of SR‐μXRF, the light element capability of PIXE/PIGE under a helium flux and the spatial resolution of BSEM + EDS was used to characterize chemical composition and corrosion of glass samples (first to fourth centuries ad) from an important, but scarcely investigated, Roman region of south‐west Iberia (southern Portugal). The geochemical trends and associations of major, minor and trace elements were investigated to shed light on production techniques, the provenance of raw materials and decay mechanisms. The results, while confirming a production technique common to Roman glasses throughout the Empire—that is, a silica‐soda‐lime low‐Mg, low‐K composition, with glass additives as colouring and/or decolouring agents (Fe, Cu, Mn, Sb)—show at one site high Zr–Ti contents, suggesting a more precise dating for these glasses to the second half of the fourth century. The Ti–Fe–Zr–Nb geochemical correlations in the pristine glass indicate the presence of minerals such as ilmenite, zircon, Ti‐rich Fe oxides and columbite in the sands used as raw materials for the glass former: these minerals are typical of granitic‐type source rocks. The unusually high K content in the corrosion layers is consistent with burial conditions in K‐rich soils derived from the alteration of 2:1 clays in K‐bearing rock sequences.