Beryllium Powder Research Articles

Investigating characteristics of neutrons from accelerator-driven compact source using novel target of compressed beryllium-powder

The study was conducted at the cyclotron laboratory of the Tomsk Polytechnic University, on the use of a new form of target utilized in the production of fast-neutrons. The flux of fast-neutrons emitted by a novel target of beryllium powder compressed in a copper mold has been measured using Al and Fe foils as detectors. The change in the neutron flux in terms of the deuteron energy was studied by using thin aluminum filters. The increase of neutron flux reached about 60% when comparing with results obtained previously by our team when only the Be-target was used, this increase referred to the reaction Cu (n, 2n). In addition, comprehensive experimental graphs were obtained using our results beside other results from related literatures. It was found that they almost agree with the experimental results from the previous studies at energies less than 12 MeV, but then the neutron flux starts to increase when using a target of Be-powder compressed in a copper mold. The difference may become greater at energies above 15 MeV and the enhancement could be many times larger. Furthermore, fitted curves and their equations were obtained for the neutron flux as a function of deuteron-energy in the energy-range between 0.5 and 50 MeV. Also, the average energy of neutrons can be calculated from the derived equations for deuteron-ions in the energy-range from 2.6 to 40 MeV. The results of this study are new and promising, so that when confirming these results at higher energies above 15 MeV, we can obtain a greater neutron yield when using a target of Be-powder compressed in a copper mold or other metals with higher cross section of the reaction (n, 2n). The high intensity beams of fast-neutrons could be employed in many crucial applications, such as radiotherapy, production of radioactive isotopes, and more.

Effect of Interfacial Strength on Mechanical Behavior of Be/2024Al Composites by Pressure Infiltration.

In this paper, two kinds of Be/2024Al composites were prepared by the pressure infiltration method using two different beryllium powders as reinforcements and 2024Al as a matrix. The effect of interfacial strength on the mechanical behavior of Be/2024Al composites was studied. Firstly, the microstructure and mechanical properties of the two composites were characterized, and then the finite element analysis (FEA) simulation was used to further illustrate the influence of interfacial strength on the mechanical properties of the two Be/2024Al composites. The mechanical tensile test results show that the tensile strength and elongation of the beryllium/2024Al composite prepared by the blocky impact grinding beryllium powder (blocky-Be/2024Al composite) are 405 MPa and 1.58%, respectively, which is superior to that of the beryllium/2024Al composite prepared by the spherical atomization beryllium powder (spherical-Be/2024Al composite), as its strength and elongation are 331 MPa and 0.38%, respectively. Meanwhile, the fracture of the former shows brittle fracture of beryllium particles and ductile fracture of aluminum, while the latter shows interface debonding. Further FEA simulation illustrates that the interfacial strength of the blocky-Be/2024Al composite is 600 MPa, which is higher than that of the spherical-Be/2024Al composite (330 MPa). Therefore, it can be concluded that the better mechanical properties of the blocky-Be/2024Al composite contribute to its stronger beryllium/aluminum interfacial strength, and the better interfacial strength might be due to the rough surface and microcrack morphology of blocky beryllium particles. These research results provide effective experimental and simulation support for the selection of beryllium powder and the design and preparation of high-performance beryllium/aluminum composites.

Investigation on the compression properties of semi-solid Be-Al alloy

The uniaxial compression experiment was performed on semi-solid Be-50Al alloys, which was prepared with spherical beryllium powder and aluminum powder. Two characteristic stages of the deformation are identified. In the former stage, the stress decreases from the peak stress to a steady state stress. In the latter stage, the stress increases with different slopes. The ultimate stress improves from 1.5 MPa to70 MPa with the deformation amounts increase from 30% to 70%. The distribution of solid Be is the main factor of influencing the ultimate stress.

Probing yields and angular distributions of Be(d,n) neutrons with novel target of compressed beryllium-powder

A comprehensive study was conducted in the Cyclotron laboratory at National Research Tomsk Polytechnic University on the use of a new type of target utilized in the production of fast-neutrons. The flux and spectra of the fast-neutrons emitted by a novel target of compressed beryllium powder were studied. The neutron angular distribution was measured using Fe and Al foils as detectors in different angular situations of the target relative to the incident deuteron beam. It was found that there are some discrepancies in the neutron flux at 0° degree for the detectors, up to about 20% for different target-beam angle. Likewise, the flux of neutrons in the energy range between 1 and 6 MeV make up about 83% of the total flux. Compering with previous works using solid target, we found an increase of nearly twice the yield of fast neutrons. And there is a probability that increase would rise steadily as the deuteron energies exceed 12 MeV as was the case in our work. The results of this study are new and promising and we can obtain a relatively greater neutron yield when using a compressed powder target. This is reflected positively on many applications that use fast-neutron beams, such as radiotherapy, radioactive isotopes, and even nuclear fusion experiments, among others.

Study of beryllium hardening obtained by powder metallurgy

In the first part of the article the results of the study of powder hardening processes occurring during beryl powders consolidation by the hot pressing method are shown. The dependences of the content and morphology of the hardening phase depending on the content of low-melting impurities on the sintered Beryllium powder grains surface have been studied. A hypothesis is proposed that explains the transition of an oxide film from an amorphous to a crystalline state – devitrification, and the effect of low-melting impurities on the mechanism of the devitrification process and, as a consequence, on the effect of "dispersion-grain boundary" hardening. This hypothesis is based on theoretical confirmation with the provision of graphic material demonstrating the process of devitrification, accompanied by a dispersed-grain-boundary hardening mechanism. The final results of statistical processing carried out on industrial batches showing the dependence of the impurities content influence on the properties of hot-pressed beryllium are presented. In the second part of the article the results of studying the effect of hardening of beryllium obtained in the process of sintering by the method of hot isostatic pressing (HIP) are shown depending on the temperature of powders consolidation. Based on the results of electron microscopic studies, the dynamics of the reinforcing phase formation at the grain boundaries of sintered beryllium is shown. The quantitative dependence of the precision elastic limit and the conditional yield stress of gas-statically compressed beryllium on the size of the strengthening beryllium oxide particles and the consolidation temperature of the powders have been established. The resulting equation gives a description of the "dispersed-grain-boundary" hardening mechanism of isostatically pressed beryllium. All dependencies are also represented by graphic material reflecting the essence of the research.

Study of Reinforcing Phase Formation at the Grain Boundaries of Sintered Beryllium

In this paper we present the results of studies of the effect the state of grain boundaries formed in consolidation of beryllium powders by vacuum hot pressing has on the strength properties of sintered beryllium. The dependences of the morphology, elemental composition, and structure of the dispersed strengthening phase, beryllium oxide, on the content of low-melting impurities at the grain boundaries of sintered beryllium were studied using scanning electron microscopy and X-ray microspectral analysis. A new hypothesis that explains the difference in the morphology and structure of reinforcing particles based on the features of the transition of amorphous beryllium oxide to the crystalline state (devitrification) at grain boundaries of metallic beryllium is proposed. It has been theoretically substantiated and experimentally confirmed that the devitrification mechanism can be homogeneous or heterogeneous, depending on the content and ratio of silicon and aluminum impurities. This difference determines the formation of either finely dispersed high-strength reinforcing particles of beryllium oxide or large and less strong oxide clusters. Changes in the morphology and structure of reinforcing oxide particles at the grain boundaries of metallic beryllium, in turn, affect the dynamics of grain growth in the beryllium microstructure during vacuum hot forming processes and, ultimately, the effect of grain-dispersed hardening of sintered beryllium. The results of testing the mechanical properties of industrial hot-pressed blanks of powders with fineness less than 56 μm to determine the effect of various factors (impurity content, their ratio, and particle size of the initial powders) on the strength properties of hot-pressed beryllium are statistically processed. The adequacy of the regularities is estimated using the coefficients of the approximation accuracy, which confirms the conclusions of the theoretical and experimental analyses of the studied problem. One complex indicator of the initial powder quality which makes it possible to predict the strength properties of hot-pressed beryllium is validated based on the statistical studies. The results substantiate new possibilities for controlling the mechanical properties of sintered beryllium for various purposes.

Research of reinforcement phase formation on the borders of sintered berillium grains

The paper presents the results of studying the effect of the state of grain boundaries (formed in the consolidation of beryllium powders by vacuum hot pressing on the strength properties of sintered beryllium. Scanning electron microscopy and X-ray spectral microanalysis were used to study the dependences of the morphology, elemental composition and structure of a dispersion hardening phase - beryllium oxide – on the content of low-melting impurities at the grain boundaries of sintered beryllium. A new hypothesis is proposed to explain the difference in the morphology and structure of reinforcing particles based on the transition features of amorphous beryllium oxide to a crystalline state (devitrification) at the grain boundaries of metallic beryllium. It is theoretically substantiated and experimentally confirmed that the devitrification mechanism can be homogeneous or heterogeneous depending on the content and ratio of silicon and aluminum impurities. This difference leads to the formation of either finely dispersed high-strength reinforcing particles of beryllium oxide or large, lower-strength oxide clusters. Changes in the morphology and structure of reinforcing oxide particles at the metallic beryllium grain boundaries, in its turn, influence the dynamics of beryllium microstructure grain growth during vacuum hot forming and, ultimately, the effect of dispersed grain-boundary hardening of sintered n beryllium. The paper provides the statistically processed results of testing the mechanical properties of industrial hot-pressed blanks produced of less than 56 μm powders to determine the effect of various factors (the content of impurities, their ratio and particle size of the initial powders) on the strength properties of hot-pressed beryllium. The adequacy of the obtained regularities was evaluated using the approximation confidence coefficients and confirmed the conclusions made in the theoretical and experimental analysis of the research problem. The statistical studies substantiated a comprehensive quality indicator of initial powders in order to predict the strength properties of hot-pressed beryllium. The results obtained substantiate new possibilities for controlling the mechanical properties of sintered beryllium for various purposes.

Effect of plasma sintering on densification and oxygen content of beryllium powder

Beryllium has attracted a great attention as multiplier in fusion reactors and moderator and reflector in fission reactors.The use of plasma-sintering method has been suggested as a way to fabricate beryllium specimens which have similar properties with those produced by conventional methods (e.g., hot pressing and hot isostatic pressing).In general, the plasma-sintering process (PSP but also known as spark plasma sintering, SPS, or pulsed electric current sintering - PECS) consists of applying uniaxial pressure and pulsed current. It is considered that the pulsed current activates particle surfaces and eliminates impurities prior to a common thermomechanical treatment. However, only scarce information on its effect from the viewpoints of its contribution to densification by uniaxial pressing and oxygen content is available and verification of its effect is still needed for pure beryllium. Since the plasma activation could be a useful process to eliminate the impurities by recycling of radioactive materials, its effect should be also taken into consideration.In this study, the influence of parameters of the pulsed current on compaction of beryllium powder and oxygen content of fabricated samples was investigated. The perspectives for the further use of PSP operation from the point of view of its influence on fabrication parameters and reprocessing of the beryllium-based radioactive waste are discussed in the final part of this paper.

Synthesis of ultrafine beryllium powder of high purity by pyrolysis of di-t-butylberyllium etherate

Ultrafine beryllium (Be) powder of high purity was successfully synthesized by the pyrolysis of high-purity di-t-butylberyllium etherate (t-Bu2Be·Et2O) in elevated solvent. Scanning electron microscopy (SEM) shows that the powder is near-spherical. The most probable size of Be powder slightly decreases from 1.8μm to 1.2μm when the pyrolysis temperature increases from 202°C to 214°C and obviously decreases to 0.4μm as further increases to 230°C. X-ray diffraction (XRD) indicates that the powder has a single phase of α-Be with average crystallite size of 19.8nm–21.5nm. The total content of metal impurities in the powder is 6.8ppm–94.0ppm by inductively coupled plasma (ICP) determination.

Internal Mechanism Analysis of Modeling on Particles Size Distribution Characteristics of Impact Attrition Beryllium Powders

Abstract Based on the particle morphology of beryllium (Be) powders produced by impact attrition, a physics model has been established for describing the particle size distribution, which has only one parameter with the definite physical meaning. Two important internal mechanisms are considered: firstly, the distribution of existing state of particles with different original kinetic energy should obey the Maxwell-Boltzmann distribution after impacting, which means that big particles are unstable for their being at higher energy level, therefore they are easy to be fractured into smaller pieces in impact attrition process, and this influencing factor can be described as the negative exponential function of particles size; secondly, the tendency to remain low surface energy requires that Be powders should keep big volume as much as possible, and this influencing factor is defined as the cube function of particles size. The actual size distribution of Be particles is resulted from the competition between these two factors. Calculating result from the model is in good agreement with data from measurement.

Model Analysis on Particles Size Distribution of Beryllium Powder

A physics model was established for describing the particle size distribution of beryllium (Be) powder produced by impact attrition milling. In this model, two factors were considered: the first, the distribution of existing state of particles with different original kinetic energy should obey the Maxwell-Boltzmann statistics after impacted, it was that, being at higher energy level made big particles unstable, which were easy to be fractured into smaller pieces in impact attrition process, this influencing factor described as the negative exponential of particles size; the second, the tendency to remain low surface energy needed particles should keep big volume as much as possible, this effect defined as the cube of particles size. The actual particle size distribution of Be powder was resulted from the competition between these two factors. Calculating result from the model was in good agreement with data from measurement.

Be3(μ3‐O)3(MeCN)6{Be(MeCN)3}3](I)6 – ein Berylliumkomplex mit Cyclo‐(Be3O3)‐Kern und sein Hydrolyseprodukt [Be(H2O)4](I)2·2MeCN

AbstractSingle crystals of [Be3(μ3‐O)3(MeCN)6{Be(MeCN)3}3](I)6·4CH3CN (1·4CH3CN) were obtained in low yield by the reaction of beryllium powder with iodine in acetonitrile suspension, which probably result from traces of beryllium oxide containing the applied beryllium metal. The compound 1·4CH3CN forms moisture sensitive, colourless crystal needles, which were characterized by IR spectroscopy and X‐ray diffraction (Space group Pnma, Z = 4, lattice dimensions at 100(2) K: a = 2317.4(1), b = 2491.4(1), c = 1190.6(1) pm, R1 = 0.0315). The hexaiodide complex cation 16+consists of a cyclo‐Be3O3 core with slightly distorted chair conformation, stabilized by coordination of two acetonitrile ligands at each of the beryllium atoms and by a {Be(CH3CN)3}2+ cation at each of the oxygen atoms. This unique coordination behaviour results in coplanar OBe3 units with short Be–O distances of 155.0 pm and 153.6 pm on average of bond lengths within the cyclo‐Be3O3 unit and of the peripheric BeO bonds, respectively. Exposure of compound 1·4CH3CN to moist air leads to small orange crystal plates of [Be(H2O)4]I2·2CH3CN (3·2CH3CN). According to the crystal structure determination (Space group C2/c, Z = 4, lattice dimensions at 100(2) K: a = 1220.7(1), b = 735.0(1), c = 1608.5(1) pm, β = 97.97(1)°, R1 = 0.0394), all hydrogen atoms of the dication [Be(H2O)4]2+ are involved to form O–H···N and O–H···I hydrogen bonds with the acetonitrile molecules and the iodide ions, respectively. Quantum chemical calculations (B3LYP/6‐311+G**) at the model [Be3(μ3‐O)3(HCN)6{Be(HCN)3}3]6+ show that chair and boat conformation are stable and that the distorted chair conformation is stabilized by packing effects.

Tetra(diisopropylcarbodiimid‐N)‐Beryllium‐bis‐Triiodid und 1,3‐Diisopropyl‐2,4‐bis(isopropylimino)‐1,3‐Diazetidin

AbstractTetra(diisopropylcarbodiimide‐N)‐beryllium‐bis‐triiodide, [Be(i‐C3H7–NCN–i‐C3H7)4](I3)2 (1), was prepared from beryllium powder and iodine in diisopropylcarbodiimide suspension to give red single crystals. Compound 1 catalyzes the cyclodimerization of diisopropylcarbodiimide forming 1,3‐diisopropyl‐2,4‐bis(isopropylimino)‐1,3‐diazetidine (2), which can be isolated as colourless single crystals. 1 and 2 were characterized by X‐ray diffration and IR spectroscopy. Compound 1 crystallizes tetragonally in the space group P$\bar4$21c with two formula units per unit cell. Lattice dimensions at 193(2) K: a = b = 1292.2(1), c = 1411.2(2) pm, R1 = 0.0497. The structure of 1 consists of distorted tetrahedral dications [Be(i‐C3H7–NCN–i‐C3H7)4]2+ with site symmetry $\bar4$ and triiodide ions with site symmetry 2. Compound 2: Space group P21/c, Z = 2, lattice dimensions at 100(2) K: a = 935.2(1), b = 795.5(1), c = 1141.0(1) pm, β = 112.54(1)°, R1 = 0.0304. The structure of 2 forms centrosymmetric molecules with symmetry Ci and planar four‐membered C2N2 rings.

Direktsynthese und Kristallstruktur von [BeBr2(CH3CN)2

AbstractThe berylliumbromide‐acetonitrile complex [BeBr2(CH3CN)2] (1) was prepared in a one‐step synthesis from beryllium powder and bromine in acetonitrile at room temperature to give colourless single crystals, which were characterized by X‐ray diffraction and IR spectroscopy. Compound 1 crystallizes orthorhombically in the space group Pnma with four formula units per unit cell. Lattice dimensions at 100(2) K: a = 1253.1(1), b = 1003.7(1), c = 650.8(1) pm, R1 = 0.0217. The structure of 1 consists of monomeric molecules with site symmetry m and distances Be–Br of 214.7(5) pm and Be–N of 171.3(4) pm.

N‐Methylimidazolkomplexe des Berylliums: [Be(Me‐Im)4]I2 und [Be3(μ‐OH)3(Me‐Im)6]Cl3

AbstractTetra(N‐methylimidazole)‐beryllium‐di‐iodide, [Be(Me‐Im)4]I2 (1), was prepared from beryllium powder and iodine in N‐methylimidazole suspension to give yellow single crystal plates, which were characterized by X‐ray diffraction and IR spectroscopy. Compound 1 crystallizes tetragonally in the space group I$\bar{4}$2d with four formula units per unit cell. Lattice dimensions at 100(2) K: a = b = 1784.9(1), c = 696.2(1) pm, R1 = 0.0238. The structure consists of homoleptic dications [Be(Me‐Im)4]2+ with short Be–N distances of 170.3(3) pm and iodide ions with weak interionic C–H···I contacts. Experiments to yield crystalline products from reactions of N‐methylimidazole with BeCl2 and (Ph4P)2[Be2Cl6], respectively, in dichloromethane solutions were unsuccessful. However, single crystals of [Be3(μ‐OH)3(Me‐Im)6]Cl3 (2) were obtained from these solutions in the presence of moisture air. According to X‐ray diffraction studies, two different crystal individuals (2a and 2b) result, depending on the starting materials BeCl2 and (Ph4P)2[Be2Cl6], respectively [2a: Space group P21/n, Z = 4; 2b: Space group P$\bar{1}$, Z = 2]. As a side‐product from the reaction of N‐methylimidazole with (Ph4P)2[Be2Cl6] single crystals of (Ph4P)Cl·CH2Cl2 (3) were identified crystallographically (P21/n, Z = 4) which are isotypical with the corresponding known bromide (Ph4P)Br·CH2Cl2.

Tetra(N,N′‐tetramethylharnstoff)‐Beryllium‐Triiodid, [Be(TMH)4](I3)2

AbstractTetra(N,N′‐tetramethylurea)‐beryllium‐triiodide, [Be(TMU)4](I3)2 (1) was prepared from beryllium powder and iodine in N,N′‐tetramethylurea to give orange crystals, which were characterized by X‐ray diffraction and IR spectroscopy. Compound 1 crystallizes monoclinically in the space group C2/c with four formula units per unit cell. Lattice dimensions at 100(2) K: a = 1906.6(1), b = 1185.7(1), c = 1895.0(1) pm, β = 113.60(1) °, R1 = 0.0291. The structure of 1 consists of distorted tetrahedral cations [Be(TMU)4]2+ with Be–O bond lengths of 162.5(5) and 160.8(5) pm and triiodide ions without site symmetry.

Tetrapyridin‐Beryllium‐Polyiodid. Synthese und Kristallstruktur von [Be(Py)4]2(I3)2(I4)

AbstractTetrapyridine‐beryllium polyiodide [Be(py)4]2(I3)2(I4) (1) was prepared from beryllium powder and iodine in pyridine suspension to give brown crystal plates, which were characterized by X‐ray diffraction and IR spectroscopy. 1 crystallizes monoclinically in the space group C2/c with four formula units per unit cell. Lattice dimensions at 100(2)K: a = 2044.1(1), b = 1524.5(1), c = 1843.8(1)pm, β= 103.65(1)°, R1 = 0.0301. The structure of 1 consists of distorted tetrahedral dications, triiodide ions without site symmetry, and centrosymmetric linear tetraiodide ions.

Incorporation of a new design of backing seat and anvil in a Merrill–Bassett diamond anvil cell

A modification to the Merrill–Bassett miniature diamond anvil cell is reported here, with the inclusion of tungsten carbide backing seats with Boehler–Almax-cut diamonds to replace the previously used beryllium seats and (typically) modified brilliant-cut anvils. This has led to the removal of troublesome beryllium powder lines from diffraction images, while maintaining the pressure range and opening angle of the original design.

Proposed beryllium metal bounding airborne release fractions (ARFs)/rates (ARRs) and respirable fractions (RFs) for DOE facility accidents analyses

Beryllium metal has special properties for nuclear applications and is used widely within the Department of Energy (DOE) complex. Beryllium is toxic and has the potential to cause health effects (sensitization and chronic beryllium disease) to workers. Due to the type of processing involving large quantities of beryllium metal and powders and potential for significant airborne release under accident conditions, a comprehensive hazard analysis is required by DOE in a safety analysis document that evaluates potential accidents that can cause beryllium releases to the workplace and public or to the environment. The goal of the safety analysis is to identify and evaluate hazards so that appropriate controls or safeguards can be specified to protect the workers and public from potential accidents. A hazard assessment is also required to comply with 10 CFR Part 850, Chronic Beryllium Disease Prevention Program (1999) to protect the workers. DOE safety analyses include a quantitative estimate of releases and downwind concentrations for purposes of hazard classification and determination of the need for additional hazards analysis, accident analysis, and risk assessments. There are no complex-wide accepted Airborne Release Fractions (ARFs) and Respirable Fractions (RFs) that can be used to evaluate the potential downwind consequences of releases of beryllium under various accident conditions (e.g., spill, fire, stress, explosion, etc.). The purpose is to recommend DOE complex-wide ARFs and RFs that can be used to evaluate the potential downwind consequences of accidents. This paper proposes various values for ARFs and RFs that are based on review of the published information and data on the oxidation and ignition behavior of beryllium metal encased in a thin coat of non-porous, adherent oxide (“blue oxide”); the typical form of this material found in DOE facilities. Information is also presented as a function of the morphology of the metal (i.e., large, coherent, pieces; turnings/swarfs; chips/powder; and dust) because the surface to volume ratio is an important factor in evaluating both the amount of beryllium released and the potential for ignition of the metal that may increase the amount of release significantly. Guidance is also provided for the use of the DOE-HDBK-3010-94, Airborne Release Fractions/Rates and Respirable Fraction for Nonreactor Nuclear Facilities, values for oxide releases that result in a more liberal, allowable limiting airborne concentration for determining consequences and hazard classification of the facility. Detailed explanations of the proposed ARF/RF values for the various beryllium metal forms (large coherent pieces, chips/powder, turning/swarfs from processing, and dust) and other aspects of beryllium are provided in a report by Mishima et al. (April 2005). A short version of this report and a summary of the ARF/RF values are presented here.

Differences in estimates of size distribution of beryllium powder materials using phase contrast microscopy, scanning electron microscopy, and liquid suspension counter techniques

Accurate characterization of the physicochemical properties of aerosols generated for inhalation toxicology studies is essential for obtaining meaningful results. Great emphasis must also be placed on characterizing particle properties of materials as administered in inhalation studies. Thus, research is needed to identify a suite of techniques capable of characterizing the multiple particle properties (i.e., size, mass, surface area, number) of a material that may influence toxicity. The purpose of this study was to characterize the morphology and investigate the size distribution of a model toxicant, beryllium. Beryllium metal, oxides, and alloy particles were aerodynamically size-separated using an aerosol cyclone, imaged dry using scanning electron microscopy (SEM), then characterized using phase contrast microscopy (PCM), a liquid suspension particle counter (LPC), and computer-controlled SEM (CCSEM). Beryllium metal powder was compact with smaller sub-micrometer size particles attached to the surface of larger particles, whereas the beryllium oxides and alloy particles were clusters of primary particles. As expected, the geometric mean (GM) diameter of metal powder determined using PCM decreased with aerodynamic size, but when suspended in liquid for LPC or CCSEM analysis, the GM diameter decreased by a factor of two (p < 0.001). This observation suggested that the smaller submicrometer size particles attached to the surface of larger particles and/or particle agglomerates detach in liquid, thereby shifting the particle size distribution downward. The GM diameters of the oxide materials were similar regardless of sizing technique, but observed differences were generally significant (p < 0.001). For oxides, aerodynamic cluster size will dictate deposition in the lung, but primary particle size may influence biological activity. The GM diameter of alloy particles determined using PCM became smaller with decreasing aerodynamic size fraction; however, when suspended in liquid for CCSEM and LPC analyses, GM particle size decreased by a factor of two (p < 0.001) suggesting that alloy particles detach in liquid. Detachment of particles in liquid could have significance for the expected versus actual size (and number) distribution of aerosol delivered to an exposure subject. Thus, a suite of complimentary analytical techniques may be necessary for estimating size distribution. Consideration should be given to thoroughly understanding the influence of any liquid vehicle which may alter the expected aerosol size distribution.