Continuous Stiffness Measurement Research Articles

纳米压痕法确定TSV-Cu的应力-应变关系 *

为得到硅通孔电镀填充铜（TSV-Cu）的力学性能,对TSV-Cu进行了Berkovich纳米压痕实验.基于Oliver-Pharr算法和连续刚度法确定TSV-Cu的弹性模量和硬度分别为155.47 GPa和2.47 GPa;采用有限元数值模拟对纳米压痕加载过程进行反演分析,通过对比最大模拟载荷与最大实验载荷,确定TSV-Cu的特征应力和特征应变;由量纲函数确定的应变强化指数为0.4892;将上述实验结果代入幂强化模型中,确定TSV-Cu的屈服强度为47.91 MPa.最终确定了TSV-Cu的幂函数型弹塑性应力-应变关系.

Crystal growth and terahertz wave generation of organic NLO crystals: OH1

The organic nonlinear optical (NLO) crystal OH1 (2-(3-(4-hydroxystyryl)-5,5-dimethylcyclohex-2-enylidene) malononitrile) was grown by the seeded solution growth method with size up to 11×11×10mm3. The cooling rate would affect the crystal formation and lead to the different shapes of OH1 crystals. The hydrogen-bond interactions between the OH1 molecules played a prominent influence on the molecular alignment and the direction of crystal growth. Furthermore, the OH1 crystals grown from the seeds on different orientations would form different morphologies. X-ray rocking curve showed good quality of the grown crystals. Continuous stiffness measurement showed that the hardness of the OH1 (100) and (111) plane was about 0.67GPa and 0.51GPa, while the Young׳s modulus was about 9.68GPa and 11.91GPa, respectively. The transmission spectra in the range of 0.5–20μm was measured and there was a transmission window appearing in the mid-infrared waveband of 4–6μm. With the OH1 crystal obtained, continuous THz wave radiation ranging from 0.25 to 3.0THz was generated by an optical rectification method, which was two times as large as that generated from ZnTe in the low frequency band.

Nanoindentation responses of InN thin films

In the present study, the structural and nanomechanical characteristics of InN thin films are investigated by means of X-ray diffraction (XRD) and nanoindentation techniques. The InN thin films were deposited on the GaN/(0001) sapphire substrates by using the metal-organic chemical-vapor deposition (MOCVD) system. The XRD results indicated that InN thin films are pure hexagonal phase with the (002)-oriented characteristics. The “pop-ins” phenomena observed in the load–displacement curve during loading are due primarily to the activities of dislocation nucleation and propagation. Based on this scenario, an energetic estimation of dislocation nucleation is made. In addition, the hardness and Young’s modulus of InN thin film are obtained by a Berkovich nanoindenter operated with the continuous contact stiffness measurements (CSM) option. The obtained values of the hardness and Young’s modulus are 4.2±0.1GPa and 152.5±3.9GPa, respectively.

Modification of optical and mechanical surface properties of sputter-deposited aluminum thin films through ion implantation

Aluminum (Al) thin films are used widely as an electronic material in a variety of applications because of their high conductivity, optical reflectance and low cost. In the present study, helium (He) and nitrogen (N2) ions were implanted in sputter-deposited Al thin films with different doses and energies, and the changes in the film properties, such as the surface roughness, optical reflectance, hardness and Young’s modulus, were investigated. The results showed that the implantation of both ions smooth the surface of Al thin films by decreasing the hillock density, resulting in low global surface roughness. In particular, in the case of He ion implantation, the moderated degradation of optical reflectance was observed compared to the film implanted with nitrogen ion. On the other hand, excessive ion implantation increased the local (short-range) surface roughness, which deteriorated the optical reflectance of the Al films. The continuous stiffness measurement technique in nano-indentation showed that ion implantation increased the hardness near the surface. He ion implantation hardened the surface of the Al thin film, and almost 2 times higher surface hardness was achieved with an ion dose of 1018 ions/cm2 at 40 KeV.

The Influence of Indentation Conditions on Nanohardness Depth Profiles of W-C Based Coatings

The influence of different indentation parameters including loading type, loading/strain rate, frequency and amplitude on nanohardness depth profiles on DC-MS W-C based coatings thick from 300 to 850 nm were investigated with the aim to determine the best conditions for the measurement of hardness of thin films during sinusoidal loading cycle. Nanohardness tests were performed on G200 (Agilent Technologies) and NHT (CSM Instruments) nanoindenters using standard loading/unloading cycle, CMC (continuous multicycle) mode and continuous stiffness measurement method (CSM) or sinus mode, respectively. The increase of strain rate and sinus amplitude results in decrease of maxima hardness of profiles while the increase of frequency caused its increase.

Characterization of Young׳s modulus and fracture toughness of albite glass by different techniques

This work compares values of Young׳s modulus and fracture toughness of amorphous albite measured from different experimental techniques. Sodium feldspar powder was used to synthesize the albite glass. After quenching, the microstructure of the amorphous solid was analyzed via scanning electron microscopy and X-ray diffraction. Several nanoindentations on albite samples were carried out with two purposes: determination of Young׳s modulus by continuous stiffness measurement, and critical stress intensity factor by crack size evaluation. Concurrently, impulse excitation technique and three point bending single-edge notched test were adopted for providing the comparison of elasticity and toughness, respectively. Young׳s modulus measured by continuous stiffness yielded a value of 71.8±0.9GPa, which was in agreement with the value obtained by impulse excitation (72.5±1.3GPa). The fracture toughness determined by nanoindentation was slightly higher (0.86±0.06MPam1/2) than that (0.78±0.06MPam1/2) obtained by single-edge notched beam.

A contact area function for Berkovich nanoindentation: Application to hardness determination of a TiHfCN thin film

In nanoindentation, especially at very low indenter displacements, the indenter/material contact area must be defined in the best possible way in order to accurately determine the mechanical properties of the material. One of the best methodologies for the computation of the contact area has been proposed by Oliver and Pharr [W.C. Oliver, G.M. Pharr, J. Mater. Res. 7 (1992) 1564], which involves a complex phenomenological area function. Unfortunately, this formulation is only valid when the continuous stiffness measurement mode is employed. For other conditions of indentation, different contact area functions, which take into account the effective truncation length or the radius of the rounded indenter tip, as well as some fitting parameters, have been proposed. However, most of these functions require a calibration procedure due to the presence of such parameters. To avoid such a calibration, in the present communication a contact area function only related to the truncation length representative of the indenter tip defect, which can be previously estimated with high resolution microscopy, has been proposed. This model allows the determination of consistent indentation data from indenter displacements of only few nanometers in depth. When this proposed contact area function is applied to the mechanical characterization of a TiHfCN film of 2.6μm in thickness deposited onto a tool steel substrate, the direct determination of the hardness and elastic modulus of the film leads to values of 35.5±2GPa and 490±50GPa, respectively.

Nanoindentation of Mg-doped AlGaN thin films

The effects of Mg-containing precursor flow rate on the nanomechanical characteristics of the Mg-doped AlGaN thin films are investigated by using nanoindentation technique. The Mg-doped AlGaN thin films were deposited on sapphire substrates by metal–organic chemical–vapor deposition (MOCVD) with the various flow rates of 100, 200 and 600sccm of bis-(cyclopentadienyl)-magnesium (Cp2Mg) precursor. Nanoindentation results revealed apparent discontinuities (so-called multiple “pop-ins”) in the load–displacement curves, while no discontinuity was observed in the unloading segment of the load–displacement curves. The hardness and Young’s modulus of Mg-doped AlGaN thin films measured by a Berkovich nanoindenter operated with the continuous contact stiffness measurements (CSM) method indicated that both mechanical properties increased with increasing the Mg concentration with the hardness and the Young’s modulus being increased from 20.62±0.53 to 24.17±0.72GPa and from 317.48±7.82 to 364.63±17.62GPa, respectively, as the Mg concentration raised from 100 to 600sccm.

Nanostructure Variations and Their Effects on Mechanical Strength of Ni-17Mo-7Cr Alloy under Xenon Ion Irradiation

A nickel-base high-temperature alloy (Ni-17Mo-7Cr) has been characterized by nanoindentation and transmission electron microscopy to determine the changes of nanoindentation hardness and microstructural evolution under ion irradiation. Ion irradiation experiments for bulk and thin-foil specimens of Ni-17Mo-7Cr alloy were carried out at room temperature, up to 6.6 dpa, by 7 MeV Xe26+ and 1 MeV Xe20+ ions, respectively. The continuous stiffness measurement (CSM) with a diamond Berkovich indent was used to measure the depth profile of hardness. Nanoindentation results for bulk specimens showed an evident ion irradiation induced hardening phenomenon, and the nanoindentation hardness increases with increasing ion dose. High number density of nano-scale black spots and linear-like defects were observed in thin-foil specimens irradiated at 0.33 and 6.6 dpa, respectively. High-resolution transmission electron microscopy images revealed that the black spots were nano-scale solute clusters and dislocation loops, while the linear-like defects were found to be Ni, Mo and Cr-enrichment regions by using the high-angle annular dark field-scanning transmission electron microscope. The ion irradiation induced defects can be responsible for the hardening of Ni-17Mo-7Cr alloys.

Mechanical Properties of Ba1-xKxCe0.6Zr0.2Y0.2O3-δ Oxides by Nanoindentation

The microstructural and nanomechanical characteristics Ba1-xKxCe0.6Zr0.2Y0.2O3-δ (K-doped BCZY, 0.0≤x≤0.15) oxides affected by the various K doping concentrations are investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and nanoindentation techniques in this study. All BKCZY samples are produced by a combination of the citrate-ethylenediaminetetraacetic acid (EDTA) complexing sol-gel process and the composition-exchange method, formed by uniaxial pressure and sintered at 1600 oC for 4h. XRD results indicated that the BKCZY samples are pre-dominantly the perovskite-type cubic structure. The hardness and Young's modulus of BKCZY samples are measured by a Berkovich nanoindenter operated with the continuous contact stiffness measurements (CSM) mode. The results indicated that the hardness and Young's modulus of BKCZY sample decreased with increasing the K doping concentrations.

On the measurement of energy dissipation using nanoindentation and the continuous stiffness measurement technique

Abstract

Measuring Mechanical Properties of Zirconia Dental Crowns by Nanoindentation

Mechanical properties of dental materials are increasingly studied via nanoindentation testing. Due to the excellent mechanical properties, 3-mol%-Yttria-Stabilized Tetragonal Zirconia (3Y-TZP) has become an attractive high-toughness core material for fixed dental restorations. In this paper, the mechanical properties of 3Y-TZP were studied by nanoindentation. The continuous stiffness measurement (CSM) and the single load/unload cycle test controlled by displacement and load respectively were performed with a Berkovich indenter.

Mechanical Properties of Cu₂O Thin Films by Nanoindentation.

In this study, the structural and nanomechanical properties of Cu2O thin films are investigated by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) and nanoindentation techniques. The Cu2O thin films are deposited on the glass substrates with the various growth temperatures of 150, 250 and 350 °C by using radio frequency magnetron sputtering. The XRD results show that Cu2O thin films are predominant (111)-oriented, indicating a well ordered microstructure. In addition, the hardness and Young’s modulus of Cu2O thin films are measured by using a Berkovich nanoindenter operated with the continuous contact stiffness measurements (CSM) option. Results indicated that the hardness and Young’s modulus of Cu2O thin films decreased as the growth temperature increased from 150 to 350 °C. Furthermore, the relationship between the hardness and films grain size appears to closely follow the Hall-Petch equation.

Investigation of the Mechanical Properties of Nanocrystalline Cemented Carbides by Nano-Indentation Technique

The nanocrystalline WC-Co bulk material with a relative density of 98.5% was prepared by combing in-situ reduction and carbonization reactions and spark plasma sintering method. Using continuous stiffness measurement method in the nanoindentation technique, the high precision modulus and hardness of the material were measured.

Characterization of Nanomechanical, Ferroelectric, and Piezoelectric Properties by Nanoindentation and Piezoresponse Force Microscopy of PbTiO3 Thin Films

Lead titanate PbTiO3 films were deposited onto Pt(111)/Ti/SiO2/Si(100) substrates by the aerosol assisted chemical vapor deposition (AA-CVD) process followed by thermal annealing at 550 °C for 12 h. Piezoresponse force microscopic observations revealed a nano laminar domain structure in the PbTiO3 grains, and we attribute the lamellar domains to 180 and 90° ferroelectric domains. The polarization-switching mechanism of the domains in the representative PbTiO3 film under an external electric fields has also been studied, and it was revealed that a large-area polarization switching is usually accompanied by the appearance of a new direction of 90° domains in order to reduce the stress in the grains. Finally, nanomechanical properties such as the elastic modulus and hardness were evaluated by nanoindentation using the continuous stiffness measurement technique.

Depth-sensing indentation applied to polymers: A comparison between standard methods of analysis in relation to the nature of the materials

Mechanical data (hardness and elastic modulus) from instrumented indentation testing are often extracted assuming linear elasticity in the initial portion of the unloading. The method is nowadays widely accepted as a convenient tool to interpret depth-sensing data, however it is a matter of controversy when applied to polymer materials due to their time-dependent behavior. More recently, Loubet and co-workers applied continuous stiffness measurements (CSM), consisting of superimposing a small oscillation to the quasi-static component of loading, to the study of the mechanical properties of polymers and proposed a new model to account for the apparent increase in the contact area detected at the first stages of contact. The present work offers a comparative study between the Loubet’s model using CSM and the procedure yielding a single reading from the onset of unloading. A wide range of thermoplastic polymer materials including glassy and semicrystalline polymers have been investigated. The most important equations employed for each method are summarized and the advantages and disadvantages of employing one procedure or the other are discussed. The differences found between the results obtained from both approaches are discussed in relation to the nature of the polymer material. A comparison between mechanical data extracted from indentation measurements and from classical dynamic mechanical analysis is offered.

Nanocomposite of Polyaniline with the photoadduct of potassium hexacyanoferrate and pyridine ligand: Structural, electrical, mechanical and thermal study

This work involves the synthesis of polyaniline nanocomposite with photoadduct of potassium hexacyanoferrate and pyridine achieved through ball milling, photochemical route, and by oxidative polymerization technique using ammonium persulphate as oxidizing agent .The photoadduct has been synthesized by photoirradiation followed by substitution with pyridine ligand. The photoaquation, substitution and successful synthesis has been proved by recording pH, UV–visible spectra, FTIR and XRD. The as synthesized nanocomposite has been subjected to various characterization techniques like elemental analysis, UV–visible spectra, FTIR, XRD, and SEM. XRD of photoadduct shows crystalline structure which has been retained in the nanocomposites also. Parameters like crystallite size, dislocation density, microstrain, d-spacing, were evaluated. Thermal study was carried out by recording TGA/DTG, showing very high thermal stability of nanocomposite as compared to PANI which can be due to strong interaction between polymer chain and photoadduct, hence the material can be used for high temperature applications electrical conductivity was measured by four probe conductivity meter. Conductivity of nanocomposite was found to be many orders of magnitude higher than that of polyaniline. The nanomechanical properties were investigated with an MTS Nano-Indenter XP by using continuous stiffness measurement (CSM) technique. Mechanical properties of pure PANI has improved with doping of photoadduct.

An analysis of the elastic properties of a porous aluminium oxide film by means of indentation techniques

The elastic modulus of thin films can be directly determined by instrumented indentation when the indenter penetration does not exceed a fraction of the film thickness, depending on the mechanical properties of both film and substrate. When it is not possible, application of models for separating the contribution of the substrate is necessary. In this work, the robustness of several models is analyzed in the case of the elastic modulus determination of a porous aluminium oxide film produced by anodization of an aluminium alloy. Instrumented indentation tests employing a Berkovich indenter were performed at a nanometric scale, which allowed a direct determination of the film elastic modulus, whose value was found to be approximately 11GPa. However, at a micrometric scale the elastic modulus tends toward the value corresponding to the substrate, of approximately 73GPa. The objective of the present work is to apply different models for testing their consistency over the complete set of indentation data obtained from both classical tests in microindentation and the continuous stiffness measurement mode in nanoindentation. This approach shows the continuity between the two scales of measurement thus allowing a better representation of the elastic modulus variation between two limits corresponding to the substrate and film elastic moduli. Gao's function proved to be the best to represent the elastic modulus variation.

Structural and nanomechanical properties of BiFeO3 thin films deposited by radio frequency magnetron sputtering

The nanomechanical properties of BiFeO3 (BFO) thin films are subjected to nanoindentation evaluation. BFO thin films are grown on the Pt/Ti/SiO2/Si substrates by using radio frequency magnetron sputtering with various deposition temperatures. The structure was analyzed by X-ray diffraction, and the results confirmed the presence of BFO phases. Atomic force microscopy revealed that the average film surface roughness increased with increasing of the deposition temperature. A Berkovich nanoindenter operated with the continuous contact stiffness measurement option indicated that the hardness decreases from 10.6 to 6.8 GPa for films deposited at 350°C and 450°C, respectively. In contrast, Young's modulus for the former is 170.8 GPa as compared to a value of 131.4 GPa for the latter. The relationship between the hardness and film grain size appears to follow closely with the Hall–Petch equation.

Effect of the continuous stiffness measurement on the mechanical properties extracted using spherical nanoindentation

The effects of the superimposed oscillating load while using the continuous stiffness measurement (CSM) technique on the extracted indentation stress–strain (ISS) curves were systematically investigated using spherical nanoindentation tests performed on a variety of samples, using probes of 1 and 100μm radii. Particular care was afforded to the corrections that were needed on the load, displacement and stiffness signals to account for the effect of the superimposed oscillations. A decrease in the oscillation frequency from the commonly used 45Hz caused the measured stiffness values to decrease. This resulted in questionable high strain hardening values in the ISS curves. The noise levels in the recorded stiffness signal were significantly higher while using an oscillation amplitude of 1nm. It was concluded that these observations are artifacts of the machine dynamic control systems and do not represent the material’s true behavior. The CMS signal with a 45Hz oscillation frequency and 2nm amplitude appears to produce most reasonable values of stiffness values and is therefore the best choice for reliably extracting ISS curves for the materials studied.