Grain Size Research Articles

Mechanism of microstructure and properties evolution of 2195 Al-Li alloy during radial-direction hot compression and heat treatment: Determined by shape, size and rotation of grains

Mechanism of microstructure and properties evolution of 2195 Al-Li alloy during radial-direction hot compression and heat treatment: Determined by shape, size and rotation of grains

Effect of composition, temperature, and grain size on mechanical behavior and deformation mechanism of lightweight magnesium alloy.

To address the severe fuel crisis and environmental pollution, the use of lightweight metal materials, such as AZ alloy, represents an optimal solution. This study investigates the mechanical behavior and deformation mechanism of AZ alloys under uniaxial compressive using molecular dynamics (MD) simulations. The influence of various compositions, grain sizes (GSs), and temperatures on the compressive stress, the ultimate compressive strength (UCS), compressive yield stress (CYS), Young's modulus (E), shear strain, phase transformation, dislocation distribution, and total deformation length is thoroughly examined. The results show that although AZ91 has the highest Al content, it exhibits the lowest UCS, CYS, and fraction atoms with shear strain larger than 0.2 (FSS0.2) compared to AZ31 and AZ61. At the same time, the total dislocation length of AZ31 is the largest. The effect of GS and temperature on the mechanical response and deformation mechanism of AZ31 alloy indicates that a GS of 7.6nm is the critical value to determine the mechanical properties and deformation intensity of AZ31 alloy. Moreover, the E, UCS, and CYS values decrease gradually as temperature increases. The compressive stress, E, UCS, CYS, and FSS0.2 of single crystalline AZ31 are higher than those of polycrystalline AZ31 with all GSs. The MD simulation results show that the sample experiences the formation of stacking faults at both single crystalline and polycrystalline AZ31 while forming the shear band at the single crystalline, leading to strong oscillations in compressive stress. In contrast, polycrystalline AZ31, across all GSs, exhibits high shear strain zones, causing oscillations in compressive stress. The ATOMSK program is used to create the polycrystalline AZ structures. The MD method is employed to investigate the influence of various compositions, GSs, and temperatures on the mechanical properties and deformation mechanism of AZ alloys. All the simulations are performed by LAMMPS software. The visualization tool (OVITO) is used to inspect, analyze, and illustrate the simulation results. The EAM potential is applied to the interactions between Al-Zn, Al-Mg, and Zn-Mg.

Geotechnical characterization of soil-rubber mixtures with well-graded gravel

Shredded rubber from waste tyres has progressively been adopted in civil engineering due to its mechanical properties, transforming it from a troublesome waste into a valuable and low-cost resource within an eco-sustainable and circular economy. Granular soils mixed with shredded rubber can be used for lightweight backfills, liquefaction mitigation, and geotechnical dynamic isolation. Most studies have focused on sand-rubber mixtures. In contrast, few studies have been conducted on gravel-rubber mixtures (GRMs), primarily involving poorly-graded gravel. Poorly-graded gravel necessitates selecting grains of specific sizes; therefore, from a practical standpoint, it is of significant interest to examine the behaviour of well-graded gravel and shredded rubber mixtures (wgGRMs). This paper deals with wgGRMs. The results of drained triaxial compression tests on wgGRMs are analysed and compared with those on GRMs. Stress-strain paths toward the critical state and energy absorption properties are evaluated. The tested wgGRMs exhibit good shear strength and remarkable energy absorption properties; thus, they can be effectively utilised in several geotechnical applications.

Grain size characterization of nickel alloy 718 with optimized metallographic sample preparation route followed by a novel etching technique

Abstract A suitable etching technique can distinguish the appearance of microscopic features such as grain boundaries (GBs), annealing twins (TBs), and precipitates, unlike nonmetallic inclusions, voids, and microcracks, which are visible in as-polished conditions. The difficulties arise when a semi-automatic or automatic grain size (GS) analyzer detects the TBs in addition to GBs concurrently. This study introduces a novel etching technique that has selectively highlighted the GBs without or faintly emphasizing TBs in heat-treated additively manufactured (AM) and wrought nickel alloy 718, respectively. The authors then measured the GS using the comparison and intercept procedure (lineal and Abrams three-circle) according to ASTM E112-2013. Moreover, the comparative study identified the comparison procedure as the most effective approach based on accuracy, post-processing, and time consumption. However, it had limitations in terms of precision and applicability. In contrast, the intercept procedure emerged as the preferred choice for higher accuracy demands.

Zn-Mn-Mg alloy with superior mechanical properties and antibacterial performance

Zn-Mn alloys are particularly promising biodegradable implant materials, but they are plagued by poor mechanical performance. In this work, a Zn-Mn alloy with ultrahigh strength and excellent ductility was achieved through addition of trace Mg (0.1 wt%) and equal channel angular pressing (ECAP). Specifically, the ECAP processed Zn-0.5Mn-0.1 Mg alloy exhibits an ultimate tensile strength (UTS) of 428 MPa, which is highest ever achieved in Zn-Mn-based alloys, along with a good elongation (EL) of 39%. In addition, the alloy exhibits excellent antibacterial performance against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Trace Mg addition results in the formation of Mg2Zn11 and MgZn2 nano-precipitates in the alloy, which effectively pins grain growth during dynamic recrystallization (DRX) and postpones the inverse Hall–Petch relation. Consequently, the alloy possesses quite fine grains of an average grain size (AGS) of 0.71 μm, much smaller than that of its counterpart without Mg (AGS = 2.54 μm). The ultrahigh strength of the alloy is mainly ascribed to grain boundary strengthening and precipitation strengthening. The remarkable ductility of the alloy is related to deformation twinning suppression, pyramidal < c + a > slip activation, and low dislocation density.

Annealing Behavior of Electroplated Nano-grained Copper

Copper bonding (direct and hybrid) in interconnection – one of these concepts, will benefit from an electroplated nanograined copper. The copper grain size for this purpose should not change for up to 1 month at RT, but increases up to 10 times under bonding conditions. It is desirable that the electroplated copper has low impurities and achieves strong Cu2Cu bonds at low temperatures without voids. The electrodeposition of nanograined copper with IntraCu® SC-4 electrolyte was investigated with voltammetry, SEM, EBSD, GDEOS and SIMS methods. The effect of current density, grain size of seed layer and geometry of vias on the structure of nanograined copper was established. The resulting coatings were characterized for: • Grain size (less than 150nm) stability at room temperature storage - unchangeable more than 3 weeks (almost suppressed self-annealing behavior); • Increasing of the size of copper grains after different annealing temperature and duration – from 120⁰ to the 260⁰ C, from 1 to 10 hours, also with different annealing profile. Size of grains is shown to increase more than 7 times-10, even at lower than 200⁰ C temperature A linear relationship between the impurities, voids in the layer and the concentration of additives (as well current density) was found. According to this relation, the size, stability in time, impurities and annealing behavior of the nanocrystals could be predicted and controlled.

Development of a Finite Element Model for the HAZ Temperature Field in Longitudinal Welding of Pipeline Steel

In this study, a novel hybrid heat source model was developed to simulate the welding temperature field in the heat-affected zone (HAZ) of X80 pipeline steel. This model replicates welding conditions with high accuracy and allows flexible three-dimensional adjustments to suit various scenarios. Its development involved the innovative integration of microstructural crystallography information with a multi-scale calibration and validation methodology. The methodology focused on three critical aspects: the weld interface morphology, the location of the Ac1 temperature, and the size of prior austenite grains (PAG). The morphology of the weld interface was calibrated to align closely with experimental observations. The model’s prediction of the Ac1 location in actual welded joints exhibited a deviation of less than ±0.3 mm. Furthermore, comparisons of reconstructed PAG sizes between thermal simulation samples and actual HAZ samples revealed minimal discrepancies (5 μm). Validation results confirmed that the calibrated model accurately describes the welding temperature field, with reconstructed PAG size differences between simulation and experimental results being less than 9 μm. These findings validate the accuracy of the calibrated model in predicting welding temperature fields. This research introduces a novel framework for the development of heat source models, offering a robust foundation for improving welding performance and controlling microstructure in different regions during the welding process of high-strength low-alloy (HSLA) steel.

Enhancement of Fracture Toughness of NiTi Alloy by Controlling Grain Size Gradient.

Fracture toughness is a critical indicator for the application of NiTi alloys in medical fields. We propose to enhance the fracture toughness of NiTi alloys by controlling the spatial grain size (GS) gradient. Utilizing rolling processes and heat treatment technology, three categories of NiTi alloys with distinct spatial GS distributions were fabricated and subsequently examined through multi-field synchronous fracture tests. It is found that the one with a locally ultra-high GS gradient (20 nm-3.4 μm) has significantly enhanced fracture toughness, which is as high as 412% of that of the normally distributed nano-grains with an average GS of 8 nm and 178% of that of the coarse-grains with an average GS of 100 nm. Theoretical analysis reveals that in such a gradient structure, phase transition in the coarse-grained matrix greatly absorbs the surface energy of subcritical and stable propagation. Meanwhile, the locally non-uniform GS distribution leads to deviation and tortuosity of the crack path, increasing the critical fracture stress. Furthermore, the nanocrystalline clusters distributed in the form of network nodes reduce the stress intensity factor due to their higher elastic modulus compared to the coarse-grained matrix. This work provides guidance for developing new gradient nanostructured NiTi alloys with high fracture toughness.

Anatomical and palynological peculiarities of rare species Hyacinthella atropatana (Hyacinthaceae) in Armenia

Hyacinthella atropatana (Hyacinthaceae) is endemic to South Transcaucasia and is also listed in the Red Book of Plants of Armenia under the EN (Endangered) category. There are three known locations of this species, namely the Darelegis and Meghri floristic regions (Armenia) and Nakhchivan (Azerbaijan). The comparative anatomical analysis of H. atropatana specimens from both Armenian populations was conducted for the first time. The results revealed no anatomical differences between the examined specimens. The observed anatomical features, including the mechanical tissue in the scape and palisade tissue in the leaf, underscore the species’ xerophilic adaptations. Our research contributes also novel quantitative data to supplement existing literature. An evaluation of the species’ anatomical traits in relation to other investigated Hyacinthella and Scilla species substantiates H. atropatana’s closest structural similarity to the genus Hyacinthella, particularly regarding scape and leaf anatomy. At the same time, H. atropatana was distinguished from the representatives of both genera by having the smallest number of vascular bundles in both the scape and the leaf, as well as a smaller number of cortex layers in the scape. The data obtained confirmed the previous opinion on the uniqueness of this species. A comprehensive study of the pollen characteristics of H. atropatana was conducted also for the first time. It revealed a noticeable palynomorphological similarity between the two Armenian populations, as well as between samples collected in Armenia and Nakhchivan (Azerbaijan), which may be attributed to the considerable resemblance of their habitats. Additionally, our research established that within the Hyacinthella genus, H. atropatana is distinctive both in the size of pollen grains (somewhat larger than those noted for other studied species) and the uniqueness of pollen exine ornamentation. The data received support the previously proposed assumption about some isolation of this species within the Hyacinthella genus and its placement in a separate section, Atropatana.

Evaluation of Extra-High Translucent Dental Zirconia: Translucency, Crystalline Phase, Mechanical Properties, and Microstructures.

Highly translucent zirconia (TZ) is frequently used in dentistry. The properties of several highly translucent zirconia materials available in the market require an in-depth understanding. In this study, we assessed the translucency, crystalline phase, mechanical properties, and microstructures of three newly developed highly translucent zirconia materials (Zpex 4. m, 4 mol% yttria-stabilized zirconia: 4YSZ; Zpex Smile.m, 5YSZ; ZR Lucent ULTRA, 6YSZ). The translucency parameter (TP) was analyzed using the CIELAB system. X-ray diffraction was conducted for the crystalline phase analysis, followed by Rietveld refinement. A biaxial flexural strength test using the Weibull analysis was performed to evaluate the mechanical properties. Scanning electron microscopy, grain size distribution, and average grain size were used to analyze the microstructures. The TP content of the ZR Lucent ULTRA was the highest among the samples investigated. The Rietveld analysis revealed that the cubic zirconia phase content of the ZR Lucent ULTRA was the highest. The biaxial flexural strength of the ZR Lucent ULTRA was the lowest (622.9 MPa). The average grain size and proportion of large grains (1.0 µm < x) were the highest in ZR Lucent ULTRA. Therefore, extra-high translucent zirconia has the potential for use in anterior monolithic restorations owing to its esthetics and strength.

Significant reduction of anisotropy in stress relaxation aging and mechanical properties improvement for 2195 Al-Cu-Li alloy subjected to plastic loading

Although the plastic loading can enhance creep deformation and yield strength, the anisotropic Stress Relaxation Aging (SRA) behavior and mechanism under plastic loading remain unclear, which presents a significant challenge in accurately shaping aluminum alloy panels. In this study, the SRA behavior of 2195-T4 Al-Cu-Li alloys were thoroughly studied under initial loading stresses within the elastic (210/250 MPa) and plastic (380/420 MPa) ranges at 180 ℃ by stress relaxation and tensile tests as well as microstructure characterization. The findings reveal that compared with those under elastic loadings, in-plane anisotropy (IPA) values of the stress relaxation amount, yield strength and fracture elongation under plastic loadings are reduced by 60%-80%, 70%-90% and 72%-89%, respectively. Similarly, IPA values of precipitate size in grains and Precipitation-Free Zones (PFZ) width at grain boundaries under plastic loading decrease by 31.4% and 94.4% respectively. These results indicate plastic loading significantly weakens the anisotropic SRA behavior, owing to numerous uniformly distributed fine T1 phases and small IPA values of both T1 precipitates size and PFZ width in various loading directions. Compared with those of elastic loading-aged alloys, yield strength of plastic loading-aged alloys shows high strength-ductility because of the combined effect of closely dispersed fine T1 precipitates, narrowed PFZ and numerous sheared and rotated T1 phases at different locations during tensile process. The uniformly distributed larger Kernel Average Misorientation (KAM) and Schmidt factor values of the plastic loading-aged alloy, as well as the cross-slip generated, also help to enhance the strength and ductility of the alloy.

Synthesis and characterization of polypyrrole polymer thin film and the effect of adding silver nanoparticles (PPY/AgNPs)

In this research, a chemical oxidative polymerization process was used to prepare polypyrrole (PPY). The characterization of polypyrrole thin films pure and dopped with silver nanoparticles (AgNPs) at different weight ratios of AgNPs (i.e., 5, 10, and 15 wt%) was studied. The thin films were prepared via the drop casting method and flung down on a clean glass substrate at room temperature. Using FT-IR, XRD, and AFM, the system and facet morphology of the thin films were investigated. FTIR analysis of undoped PPY powder revealed distinctive vibrational frequencies of PPY undoped. Strong absorption bands at 3653 cm-1 (N-H stretching), 2342 cm-1 (nitridation), and peaks at 1542, 1459 cm-1 (C=C, C=N vibrations) were observed. Other peaks at 1176 cm-1 (C-N stretching), 1039, 964 cm-1 (C-H vibrations), 893, 782 cm-1 (C-H bend deformation), 670 cm-1 (C-C deformation), and 590 cm-1 (polypyrrole presence) were identified. The results showed that the FT-IR spectra of pure ppy and the spectra of PPY/AgNPs composites were similar. The single XRD data also showed that ppy is amorphous and The distinctive peak of polypyrrole was found at (2θ) 24.35◦, indicating the short-range arrangement of PPy chains the interlayer distance (d) between the measured value of spacing for PPY was 3.6599 A0. Additionally, By using AFM, the parameters Ra, R.M.S, and G.S. were determined for PPY doped AgNPs thin films. These values increased with higher doping percentages. For undoped PPY thin film, values were (2.557nm, 3.299nm, 33.40nm) while for doped films with 5%, 10%, and 15% AgNPs, values were (3.397nm, 4.859nm, 46.12nm), (9.328nm, 11.90nm, 66.33nm), and (13.87nm, 19.28nm, 86.89nm) respectively. the AFM results for all thin films of PPY undoped and composites doped with silver nanoparticles (PPY/AgNPs) demonstrated that the values of grain size (G.S.) and root-mean-square (R.M.S.) roughness average (Ra) increase as the number of AgNPs increases.

Effect of Rotational Speed on the Microstructure and Texture of Thermomechanically Affected Zone of Al6082-T6 Friction Plug Welding Joint

AbstractExperiments were performed on Al6082-T6 using friction plug welding to investigate and resolve keyhole faults. The process required using friction as supplemental heating which was from between the shoulder and base metal. Friction plug welded connections were successfully created at rotational speeds of 1600 rpm, 1800 rpm, and 2000 rpm. The weld joints have no apparent structural flaws, and the joints demonstrate distinct partition features. During them, the thermomechanically affected zone of joints displays a distinct boundary between the base metal and plug, accompanied by a pronounced, preferred orientation. It can be deduced that augmenting the plug's rotational speed, the size of grain and the composition of high-angle grain boundaries will facilitate dynamic recrystallization and lead to a more pronounced recrystallization texture composition, assuming all other parameters remain constant.

Taxonomical remarks on Solenopsis corsica (Campanulaceae) species complex, with the description of two new species from Sardinia

Taxonomical investigations on Solenopsis corsica occurring in Corsica and Sardinia revealed that it represents a species complex, within which some morphologically well distinct taxa can be recognized. The surveyed populations are closely related among them, especially for the habit, with very small leaf hairy rosettes, small-sized flowers with divaricate corolla lips. Apart from S. corsica s.str., widely spread in Corsica, other two new species, morphologically well differentiated can be recognized, they are: S. limbarae and S. corriasii, both occurring in northern Sardinia, where they are localized on the Limbara massif and in other nearby siliceous mountains. The diagnostic features that allow to distinguish these species encompass the size and shape of leaves, bracteoles, flowers, fruits, and seeds. In addition, other differences concern the shape and size of pollen grain and seed testa, as well as their micromorphology. Finally, chorology and ecology of these species are examined, as well as their detailed illustrations and an analytical key of the hitherto known Sardo-Corsican species of this genus are provided.

Prediction of the hot flow behavior of AISI 321 stainless steel during dynamic recrystallization using sine hyperbolic constitutive equation and artificial neural network

The hot compression deformation behavior of AISI 321 austenitic stainless steel were studied under the strain rate and temperature ranges of 0.001–1 s−1 and 950–1200°C. The single peak hot flow curves indicated the occurrence of dynamic recrystallization in AISI 321 steel at applied deformation conditions. The microstructural observations showing the development of equaxed austenite grains further approved the results of flow curve analysis. The average size of austenite grains, when deformation is carried out at strain rate of 1 s−1, increases from 8 μm at 950°C to 61 μm at deformation temperature of 1200°C. After microstructure analysis, the flow behavior of AISI 321 steel was modeled using sine-hyperbolic constitutive equation and feed-forward back propagation artificial neural network. The mean absolute error related to the predicted flow stress values at different strains with the sine-hyperbolic constitutive equation is more than 2, and this value is less than unity for the neural network method. The obtained results efficiently indicate that the ANN model is more accurate in predicting the flow behavior of AISI 321 austenitic stainless steel when the dynamic recrystallization is the prevailing softening mechanism.

New Estimate on the Spatial Distribution of the Youngest Toba Tuff Ash

ABSTRACTHere, we introduce a new estimate on the areal extent and volume of globally dispersed Youngest Toba Tuff ash by considering the decay of grain size and primary ash thickness (PAT). The areal extent of ash dispersal is modelled by interpolating the farthest sites in four directions. For this modelling, it is assumed that (i) PAT at the farthest newly identified site is equal to the maximum size of grains retrieved and (ii) the ash particles blanket the earth up to the farthest sites in a non‐discrete manner. The volume of ash‐fall is calculated using two approaches: (i) the Voronoi tessellation and (ii) a GIS‐aided mathematical calculation. When the Voronoi tessellation estimated a maximum and minimum volume of ash as 2089 and 1276 km3, the GIS‐aided mathematical calculation yielded 1573 and 1312 km3 of dense‐rock equivalent, respectively. Thus, the GIS method provided a more narrower range than the Voronoi method.

Influence of full-cycle heat treatment on microstructure and mechanical properties of CLF-1 steel

Based on the manufacturing requirements of tritium breeding blankets for fusion reactors, it is valuable to study the microstructure evolution and mechanical properties of CLF-1 steel, a candidate structural material, during the full-cycle heat treatment from profile to component. The full-cycle heat treatment includes isothermal annealing and multiple quenching and tempering treatments. Results indicate that multiple quenching and tempering treatments refine the size of prior austenite grains and reduce dislocation density and the width of lath martensite. With the increase in the number of quenching and tempering treatments, the CLF-1 steels exhibit a slight decrease in tensile strength while the impact toughness noticeably improves. Research has found that the effect of isothermal annealing treatment includes an increase in the size of the prior austenite grains and precipitates, as well as a change in the matrix from martensite to ferrite. As a result, the tensile strength and impact energy decrease sharply, while the ductility improves after isothermal annealing treatment. Subsequent quenching and tempering treatment can recover the microstructure and mechanical properties.

The rotational disruption of porous dust aggregates from ab initio kinematic calculations

Context. The size of dust grains in the interstellar medium follows a distribution where most of the dust mass is made up of smaller grains. However, the redistribution from larger grains towards smaller sizes, especially by means of rotational disruption, is still poorly understood. Aims. We aim to study the dynamics of porous grain aggregates undergoing an accelerated rotation, namely, a spin-up process that rapidly increases the angular velocity of the aggregate. In particular, we aim to determine the deformation of the grains and the maximal angular velocity up to the rotational disruption event by caused by centrifugal forces. Methods. We precalculated the porous grain aggregate by means of ballistic aggregation analogous to the interstellar dust as input for subsequent numerical simulations. We performed three-dimensional (3D) N-body simulations, mimicking the radiative torque spin-up process up to the point where the grain aggregates become rotationally disrupted. Results. Our simulations results are in agreement with theoretical models predicting a characteristic angular velocity, ωdisr, on the order of 108–109 rad s−1, where grains become rotationally disrupted. In contrast to theoretical predictions, we show that for large porous grain aggregates (⪆300 nm), the ωdisr values do not strictly decline. Instead, they reach a lower asymptotic value. Hence, such grains can withstand an accelerated rotation more efficiently up to a factor of 10 because the displacement of mass by centrifugal forces and the subsequent mechanical deformation supports the buildup of new connections within the aggregate. Furthermore, we report that the rapid rotation of grains deforms an ensemble with initially 50:50 prolate and oblate shapes, respectively, preferentially into oblate shapes. Finally, we present a best-fit formula to predict the average rotational disruption of an ensemble of porous dust aggregates dependent on the internal grain structure, total number of monomers, and applied material properties.

Evaluation of high-entropy (Cr, Mn, Fe, Co, Ni)-oxide nanofibers and nanoparticles as passive fillers for solid composite electrolytes

Solid-state electrolytes (SSEs) could represent the key to solve safety issues of lithium-ion batteries (LIBs). Among them, those obtained by homogenously dispersing inorganic nanofillers into a polymer matrix combine advantages of all SSE typologies. In this work, high-entropy (Cr,Mn,Fe,Co,Ni) oxide (HEO) with different morphology (nanoparticles or nanofibers) are evaluated as passive fillers for the preparation of composite polyethylene oxide (PEO)-based SSEs. By varying their preparation conditions (calcination at 400 or 800 °C for 0.5 or 2 h, followed by rapid cooling) different size and crystallization degree of the oxide grains are obtained. The results of the electrochemical testing of the PEO/HEO composites evidence the crucial role of the filler microstructure and morphology. The best results in terms of electrolyte resistance (22.5 Ω), electrochemical stability window (4.7 V), Li+ transference number (0.37) and ionic conductivity (3.0⋅10−4 S cm−1 at 65 °C) are obtained by using well crystallized HEO nanofibers with highly defective surface. The suitability of the most promising composite for practical applications is validated by successfully using it in full cell with commercial high-voltage cathode materials.

Diffusive shock acceleration of dust grains at supernova remnants

Diffusive shock acceleration (DSA) is a prominent mechanism for energizing charged particles up to very large rigidities at astrophysical collisionless shocks. In addition to ions and electrons, it has been proposed that interstellar dust grains could also be accelerated through diffusive shock acceleration; for instance, at supernova remnants (SNRs). Considering interstellar dust grains of various sizes and compositions, we investigate the possibility of grain acceleration at young SNR shocks (throughout the free expansion and Sedov-Taylor phases) and the maximum energies reached by the accelerated grains. We investigate the potential implications for the abundance of refractory species relative to volatile elements in the cosmic-ray composition. We rely on semi-analytical descriptions of particle acceleration at strong shocks, and on self-similar solutions for the dynamics of SNR shock waves. For simplicity, type Ia thermonuclear SNRs expanding in a uniform interstellar medium are considered. We find that the acceleration of dust grains at relativistic speed is possible, up to a Lorentz factor of $ $ and a kinetic energy of $E_ k nuc 10^2$ GeV/nuc for the smaller grains of size $a $ cm. We find that the subsequent sputtering of grains can produce nuclei with a sufficient rigidity to be injected in the process of diffusive shock acceleration. Such a scenario can help naturally account for the overabundance of refractory elements in the Galactic cosmic-ray composition, provided that a fraction, $ $, of dust grains swept up by an SNR are energized through DSA.