Measured Hardness Values Research Articles

Effect of CMP Slurry Chemistry on Copper Nanohardness

Nanohardness and etch rates of copper films sputter deposited onto a 30 nm tantalum coating on silicon wafers were measured after exposure to aqueous solutions containing various common chemical mechanical planarization slurry additives at different pH values. In most cases, the measured hardness values were consistent with the formation of surface films as indicated by the equilibrium potential-pH diagrams. In general, when the pH is low , hardness values are that of Cu metal or slightly higher. As the pH increases to , the hardness decreases to less than Cu metal as hydroxides form, or to higher values than Cu metal as oxides form. Exposure to solutions with glycine or ethylenediaminetetraacetic acid caused hardness values to be less than Cu metal, as areas of the surface became porous. Exposure to causes harder films in some areas and very porous soft films in other areas on the same surface, as passivation and dissolution of the surface occurs.

Densification behavior of Mo nanopowders prepared by mechanochemical processing

The sintering behavior of molybdenum (Mo) nanopowder was investigated in comparison to that of commercial Mo powder. At a sintering temperature of 1400 °C, the relative density of Mo nanopowder (94%) was found to be higher than that of commercial powder (74%). In samples of the same relative density, the measured hardness values were 2.34 GPa for nanopowder and 1.87 GPa for commercial powder. The sintered Mo nanopowder exhibited greater hardness compared with the commercial powders. The sintering mechanism and hardness are discussed based on the linear shrinkage behavior and observed microstructural characteristics.

Measurement of Wheat Hardness by Seed Scarifier and Barley Pearler and Comparison with Single‐Kernel Characterization System

ABSTRACTA new procedure based on a seed scarifier (SS) for measuring wheat hardness was described and investigated along with methods using a barley pearler (BP) and the single kernel characterization system (SKCS). Hardness measured by SS and BP is expressed as a percentage of kernel weight remaining after abrading and defined as abrasion resistance index (ARI). For a given sample weight, increased abrading time decreased ARI but improved the ability to differentiate variation among samples. The effect of sample moisture was also statistically significant. For improved performance of SS and BP, based on distinct patterns of relationships between surface removal rates and surface removal levels among soft and hard wheats, a combination of parameters that produces ARI values in the range of 80–20, and a run for a set of reference material are recommended. Differences in measured hardness values from SS, BP, and SKCS existed within a wheat group, but they were very much method‐dependent. Nevertheless, all methods were able to differentiate variations between soft and hard wheat groups. Because of low cost, durability, simplicity, repeatability, and aforementioned ability, SS and BP, although limited by lack of standardization and calibration procedures, can still be useful for grain hardness measurement, particularly when and where instruments for contemporary popular methods such as SKCS and near‐infrared reflectance (NIR) spectroscopy are not readily available.

Mo 나노분말의 소결거동 및 기계적 특성

The sintering behavior and mechanical property of Mo nanopowder was investigated as a function of various sintering condition. Mo oxide nanopowders were milled using a high energy ball-milling process. After the ball milling for 20h, the crystalline size of <TEX>$MoO_3$</TEX> was about 20 nm. The <TEX>$MoO_3$</TEX> nanopowders were reduced at the temperature of <TEX>$800^{\circ}C$</TEX> without holding time in <TEX>$H_2$</TEX> atmosphere. The sinterability of Mo nanopowder and commercial Mo powder was investigated by dilatometric analysis. Mo nanopowder and commercial Mo powder were sintered at <TEX>$1200^{\circ}C$</TEX> for 1 hand <TEX>$1500^{\circ}C$</TEX> for 3 h, respectively. In both specimens the measured relative density was about 95%. But the measured hardness values were 2.34 GPa for nanopowder and 1.87 GPa for commercial powder. Probably due to finer grain size of the sintered body prepared from Mo nanopowder than that prepared using commercial Mo powder. The mean grain sizes were measured to be about 1.4 mm and 6.2 mm, respectively.

Molecular Dynamics Simulation for Single Crystal Aluminum Nano-Indentation Effect by Indenter Radius

Three dimension indenter model was established to replace the ideal shape indenter model in the study of nano-indentation simulation. The limitation of short of comparing to actual condition can be solved. Single crystal aluminum surface nano-indentation on the condition of arc indenter is researched by molecular dynamic simulation. The influences of different arc radius of indenter head to testing results are discussed and compared to experiment results. The results show that The measured hardness value increases with indenter head arc radius on the same indentation depth condition. With the increase of indentation depth, the difference between measured results with changed indenter head arc radius reduces gradually. When the indentation depth increase to a certain value, the arc effect of indenter head could be ignored, the measurement will be invariable.

Microstructural investigation of the volume beneath nanoindentations in copper

The deformed volume below nanoindentations in copper single crystals with a 〈 1 1 ¯ 0 〉 { 1 1 1 } orientation is investigated. Using a focused ion beam workstation, cross-sections through nanoindentations were fabricated and examined using the electron backscatter diffraction technique. Additionally a transmission electron microscopic foil through the middle of an imprint was prepared and analysed. Due to changes in the crystal orientation around and beneath the indentations the plastically deformed zone can be visualized and compared with the measured hardness values. Furthermore, the hardness data were analysed in terms of geometrically necessary dislocations using the Nix–Gao model, where a linear relationship was found for H 2 vs. 1/ h c, but with different slopes for large and shallow indentations. The orientation “micrographs” indicate that this behaviour is associated with a change in the deformation mechanism. Consequently, two models based on possible dislocation arrangements are presented and compared with the experimental findings. For large indentations a dislocation pile-up model similar to those used to explain the Hall–Petch effect is suggested, while the model for shallow imprints uses far-reaching dislocation loops to accommodate the shape change of the indenter.

Nanoindentation shape effect: experiments, simulations and modelling

AFM nanoindentation is nowadays commonly used for the study of mechanical propertiesof materials at the nanoscale. The investigation of surface hardness of a material usingAFM means that the probe has to be able to indent the surface, but also to image it.Usually standard indenters are not sharp enough to obtain high-resolution images, but onthe other hand measuring the hardness behaviour of a material with a non-standard sharpindenter gives only comparative results affected by a significant deviation from thecommonly used hardness scales.In this paper we try to understand how the shape of the indenter affects the hardnessmeasurement, in order to find a relationship between the measured hardness of a materialand the corner angle of a pyramidal indenter. To achieve this we performed a fullexperimental campaign, indenting the same material with three focused ion beam (FIB)nanofabricated probes with a highly altered corner angle. We then compared the resultsobtained experimentally with those obtained by numerical simulations, using thefinite element method (FEM), and by theoretical models, using a general scalinglaw for nanoindentation available for indenters with a variable size and shape.The comparison between these three approaches (experimental, numerical andtheoretical approaches) reveals a good agreement and allowed us to find a theoreticalrelationship which links the measured hardness value with the shape of the indenter.The same theoretical approach has also been used to fit the hardness experimental resultsconsidering the indentation size effect. In this case we compare the measured data,changing the applied load.

Dynamic hardness and reduced modulus determination on the (001) face ofβ-Sn single crystals by a depth sensing indentation technique

In this work, the creep behaviour ofβ-Sn single crystals having different growth directions under different peak indentation testloads (10, 20, 30, 40, and 50 mN) was investigated at room temperature during indentationtests. It was found that a ‘nose’ appears in the unloading segment of the applied indentationtest load–penetration depth curve. When a ‘nose’ occurs, the apparent unloading stiffnessSu, definedas dP/dh, is negative and the reduced modulus can no longer be calculated from theOliver–Pharr method (Oliver and Pharr 1992 J. Mater. Res. 7 1564). The ‘nose’disappears when the load hold before unload is lengthened. The correction term due tothe creep is the ratio of indenter displacement rate at the end of the load holdto unloading rate (Feng and Ngan 2002 J. Mater. Res. 17 660; Tang and Ngan2003 J. Mater. Res. 18 1141). Besides, the effect of creep on contact-depthmeasurement is considered. Removal of creep effects in both contact-area and contactstiffness measurement leads to satisfactory prediction of the dynamic hardness(Hd) and reducedmodulus in β-Sn single crystals. The experimental results reveal that the measured hardness values exhibita peak-load dependence, i.e. an indentation size effect (ISE). Such peak-load dependence isthen analysed using the Meyer law, the Hays–Kendall approach, the proportional specimenresistance (PSR) model, the modified PSR (MPSR) model, and the Nix–Gao model.As a result, the modified PSR model is found to be the most effective one forHd determinationof β-Sn single crystals.

Analysis of ISE in dynamic hardness measurements of β-Sn single crystals using a depth-sensing indentation technique

The dynamic indentation tests on (001) plane β-Sn single crystals having different growth directions under different peak indentation test load (10, 20, 30, 40, and 50 mN) has been investigated. The experimental results reveal that the measured hardness values exhibit a peak-load dependence, i.e., indentation size effect (ISE). Such peak-load dependence is then analyzed using the Meyer's law, the Hays–Kendall's approach, the Elastic/Plastic Deformation model, the Proportional Specimen Resistance (PSR) model, and the Modified PSR (MPSR) model. As a result, Modified PSR model is found to be the most effective for dynamic hardness determination of β-Sn single crystals.

Modelling of friction stir welding of 7xxx aluminium alloys

A combined modelling approach was applied to predict the behaviour of high strength 7000 aluminium alloys. Thermal modelling, microstructure modelling and strength modelling were performed in succession to give some insight into the complex precipitation mechanism occurring during friction stir welding (FSW). A quantitative assessment of a recent numerical model to predict the evolution of the precipitate distribution is performed for a high strength 7449 aluminium alloy subjected to a FSW process. An optimised model calibration procedure is also presented for the 7449 alloy. The robustness of this calibration is subsequently tested by applying the model to a different 7000 series alloy, 7150 in peak-aged condition, after FSW. Microstructure predictions are found to be highly dependent on the peak temperature reached during the weld thermal cycle as well as heating and cooling rates. A range of precipitation sequences involving metastable to equilibrium phase transformation and dissolution/coarsening of precipitates are predicted. The predicted microstructures are found to be in good quantitative agreement with the characterised experimental microstructures. Predicted precipitate distributions are used to estimate the strength of the material. These predictions generally agree well with measured hardness values.

Nanoindentation Measurements of the Mechanical Properties of Ni Thin Films: Effects of Film Microstructure and Substrate Modulus

This paper presents the results of nanoindentation measurements of the hardness and moduli of normally and obliquely deposited nanocrystalline Ni films on substrates of SiO2, Si, and bulk Ni. Following an initial characterization of film microstructure and surface topography with atomic force microscopy (AFM), the paper examines the effects of film microstructure, film thickness, and substrate modulus on the measured film mechanical properties. Obliquely deposited films are shown to have lower hardness values than normally deposited films. The measured hardness values and material pile-up are also shown to depend significantly on the mismatch between the film modulus and substrate modulus. A framework is presented for quantifying the effects of substrate modulus mismatch on basic film mechanical properties.

Microstructural Investigation of the Deformation Zone below Nano-Indents in Copper

AbstractThe deformation zone below nanoindents in copper single crystals with an &lt;110&gt;{111} orientation is investigated. Using a focused ion beam (FIB) system, cross-sections through the center of the indents were fabricated and subsequently analyzed by means of electron backscatter diffraction (EBSD) technique. Additionally, cross-sectional TEM foils were prepared and examined. Due to changes in the crystal orientation around and beneath the indentations, the plastically deformed zone can be visualized and related to the measured hardness values. Furthermore, the hardness data were analyzed using the Nix-Gao model where a linear relationship was found for H2 vs. 1/hc, but with different slopes for large and shallow indentations. The measured orientation maps indicate that this behavior is presumably caused by a change in the deformation mechanism. On the basis of possible dislocation arrangements, two models are suggested and compared to the experimental findings. The model presented for large imprints is based on dislocation pile-ups similar to the Hall-Petch effect, while the model for shallow indentations uses far-reaching dislocation loops to accommodate the shape change of the imprint.

Comparison between nanoindentation and scratch test hardness (scratch hardness) values of copper thin films on oxidised silicon substrates

In this paper we measured for the first time the scratch hardness of copper thin films and compared this with hardness measured from nanoindentation. Copper films with thicknesses in the range 100 nm to 500 nm were deposited by rf magnetron sputtering on silicon substrates. Scratch hardness was determined by CSM™ scratch tester using scratch widths at low loads. The measured hardness values were compared with conventional nanoindentation hardness measurement by CSM™ nanohardness tester. At these low indentation depths there is a good correlation between the scratch hardness and the nanoindentation hardness, with an increase in hardness as the film thickness decreases.

Characterization of nanostructured Cr 2N x/Cu multilayers deposited by reactive DC magnetron sputtering

Nitride/metal nanostructured multilayers of Cr 2N x /Cu were deposited by reactive DC magnetron sputtering with various bilayer periods (2.5–30 nm) and substrate temperatures (25–400 °C). All films had a total thickness of about 470 nm and the overall chemical composition of the chromium nitride layers was close to Cr 2N 0.8. The deposited films were characterized by Rutherford Backscattering (RBS), low-angle X-ray reflectivity (XRR), high-angle X-ray diffraction (XRD) and transmission electron microscopy (TEM). The hardness and elastic modulus were measured by nanoindentation. The films deposited at 25 °C had a well-defined multilayer structure and the chromium nitride layers were found to crystallize into N-deficient fcc CrN 0.4 with traces of hexagonal Cr 2N 0.8. The layers were strongly textured with fcc CrN 0.4[002] and Cu[002] oriented along the growth direction — the fcc CrN 0.4 and Cu grains growing with a cube-on-cube relationship. The measured hardness values were about 8 GPa, and showed no dependence on the bilayer period. Higher deposition temperatures caused the multilayer structure to degrade, and at 400 °C the films were better described as non-textured nanocomposites with the chromium nitride crystallized entirely into the equilibrium hexagonal Cr 2N 0.8 structure. Hardness values of the high-temperature films in the range of 4–8 GPa were measured. Multilayer films deposited at 25 °C were found to be thermally stable against post-deposition annealing at temperatures up to about 400 °C. Annealing at 500 °C caused severe structural changes — the fcc CrN 0.4 phase transformed into hexagonal Cr 2N 0.8 accompanied by degradation of the periodic multilayer structure. The hardness decreased from the originally 8 GPa to about 5 GPa upon annealing.

Property and microstructure evaluation as a function of processing parameters: Large HY-80 steel casting for a US Navy submarine

Processing techniques can significantly alter the properties of a material and can ultimately determine whether a component will perform its function safely. This effort involves the investigation of the processing parameters of HY-80 steel castings; specifically a large HY-80 submarine casting that failed while in service due to improper processing. Samples taken from the failed casting were evaluated in the as-received condition and after exposures to various improper quench and temper scenarios that were possible during casting production. Microstructural examination and hardness measurements were used to evaluate the condition of the high strength steel and these results were correlated to Charpy impact toughness. One important result of this work indicates that hardness alone is not a good indication of material condition: the same measured hardness values yielded very different fracture behavior. The window of favorable processing parameters as defined by heat treatment temperature was clarified based on the specification requirements set by the US Navy for HY-80 castings.

Hypersonic plasma particle deposition of Si–Ti–N nanostructured coatings

Si–Ti–N coatings with various compositions were deposited on molybdenum substrates using hypersonic plasma particle deposition (HPPD). In this method, vapor phase precursors (TiCl 4, SiCl 4 and NH 3) are dissociated in a DC plasma arc and the hot gas is quenched in a rapid nozzle expansion to nucleate nanoparticles. These nanoparticles are then accelerated in hypersonic flow, causing them to deposit by ballistic impaction on a substrate placed downstream of the nozzle. Films of 10–25 μm thickness were deposited at rates of 2–10 μm/min, depending on reactant flow rates, at substrate temperatures ranging from 200 to 850 °C. When the reactant gases were premixed the coatings consisted of nc-TiN, nc-TiSi 2, nc-Ti 5Si 3 and amorphous Si 3N 4. For the unpremixed reactants case, the coatings consisted of free Si, nc-TiN and amorphous Si 3N 4. Hardness of as-deposited films was evaluated by nanoindentation of polished film cross-sections. Measured hardness values, averaged over 10–15 locations for each film, ranged from 16–24 GPa. In separate experiments with the same conditions, particle size distributions were measured by placing a sampling probe at the same location as the film substrate. The sampled aerosol was rapidly diluted and delivered to a scanning mobility particle sizer (SMPS). In-situ particle size distribution measurements confirmed that the coatings were formed by impaction of nanoparticles in the 5–15 nm range, with higher reactant flow rates producing larger particles. Focused ion beam (FIB) milling was used to observe film cross-section and porosity. For as-deposited films containing pores, in-situ plasma sintering was used to densify the film without grain growth.

Use of the focused ion beam technique to produce a sharp spherical diamond indenter for sub-10 nm nanoindentation measurements

Very sharp and well-defined rigid diamond indenters are critical for accurate sub-10 nm nanoindentation mechanical property measurements. The focused ion beam milling technique is adopted to create such a very sharp diamond indenter. With ion milling patterning, a spherical well-defined super tip is obtained at the apex of the indenter, with a radius of 53.4 nm. This sharpened indenter is applied to sub-10 nm nanoindentation measurements on fused quartz and silicon (100) samples. The elastic moduli measured at sub-10 nm depths are consistent with literature bulk values. In addition, the measured hardness values are qualitatively consistent with indentation experiments using conventional larger radii indenters. Finally, due to the small size of the indenter tip, the transition from elastic to plastic contact occurs at very shallow contact depths.

Nanoindentation measurements on Cu–Sn and Ag–Sn intermetallics formed in Pb-free solder joints

Nanoindentation testing has been used to measure the hardness and elastic modulus of Ag3Sn, Cu6Sn5, and Cu3Sn intermetallics, as well as Sn–Ag–Cu solder and pure Sn and Cu. The intermetallics were fabricated by solid-state annealing of diffusion couples prepared from a substrate (Cu or Ag) and a solder material (Sn or Sn–Ag–Cu solder), providing geometries and length scales as close as possible to a real solder joint. Nanoindentation results for the intermetallics, representing penetration depths of 20–220 nm and loads from 0.7 to 9.5 mN, reveal elastic/plastic deformation without evidence of fracture. Measured hardness values of Cu6Sn5 (6.5 ± 0.3 GPa) and Cu3Sn (6.2 ± 0.4 GPa) indicate a potential for brittle behavior, while Ag3Sn (2.9 ± 0.2 GPa) appears much softer and ductile. Using a bulk Cu6Sn5 sample, Vickers hardness testing revealed an indentation size effect for this compound, with a hardness of 4.3 GPa measured at a load of 9.8 N. An energy balance model is used to explain the dependence of hardness with load or depth, where the observation of an increasing amount of fracture with applied load is identified as the primary mechanism. This result explains discrepancies between nanoindentation and Vickers results previously reported.

Two-step penetration: a reliable method for the measurement of mechanical properties of hard coatings

A two-step penetration method using the microindentation technique is presented to investigate the mechanical properties of hard coatings in this article. This method employs a large-load indentation step, first to exhibit the influences of substrate deformation and coating thickness on the measured hardness values, and then selects a small load, based on the results of the first step to perform the measurement. Since with this small load, the measurement will not be affected by the substrate, the hardness and elastic modulus of the coatings can be obtained precisely. Experiments with TiN coatings deposited on high-speed steel substrate shows that by using this two-step penetration method, the mechanical properties of hard coatings can be measured accurately and reliably.

Scratch hardness and chipping of dental ceramics under different environments

Objective. The goal of this program was to identify promising environments that could efficiently minimize machining-induced damage of dental materials. Methods. Single point abrasion (SPA) scratch testing was used on five materials to determine the scratch hardness and amount of edge chipping as functions of chemical environment, including air, water, saline and glycerol solutions. Limited testing was also done under additional environments expected to promote chemomachining effects via crack growth promotion or debris removal. A conical diamond indenter and a conventional tungsten carbide machining tool were used in the scratch tests. One-way ANOVA analysis was used to determine statistical differences among the variables. Results. There was a consistent trend across materials that the water and saline yielded the lowest values of scratch hardness, air the next lowest, and the tests performed in glycerol yielded the highest hardness values. The measured hardness values using the conical diamond tool in the glycerol environments were about twice the hardness values measured under water and saline solutions. Environmental effects on chipping were minimal, but a linear relationship between load and per cent chipping was determined for the WC tool within the 10–50 N test range. The choice of scratch tool strongly affected scratch hardness and chipping tendency. Significance. The chemical environment had an effect on machining characteristics, but the effects were more dependent on tool interactions rather than material specific properties. As a result, it may not be possible to utilize a particular single environment to substantially improve the damage response of dental materials to machining operations. Improvements in damage resistance can be environmentally obtained, but only for shallow cuts (finishing operations).