Induced Deformation Behavior Research Articles

Establishing high temperature tribological performance and wear mechanism map of engineered in-situ TiB2 reinforced Mg-RE metal matrix composites

The high temperature sliding wear behavior of microstructurally engineering in-situ sub-micron sized TiB2 reinforced ZE41 composite was studied and compared with it’s base counterpart at varying loading conditions. The wear mechanism maps were constructed by correlating the microstructures of worn surfaces with different test parameters. The severe and catastrophic wear mechanisms like delamination and melt wear were wider in base and composite, while in the case of engineered composite, these zones are significantly narrow down. Due to the presence of thermally stable in-situ TiB2 particles and bimodal precipitates in engineered composite, the material showed sufficient resistance against wear induced deformation. Furthermore, the study established scientific knowhow on high-temperature wear induced deformation behavior by analyzing microstructural evolution in wear subsurface zone.

Deformation kinetics of coal–gas system during isothermal and dynamic non-isothermal processes

Gas-induced coal deformation plays a crucial role in fields like potential CO2 sequestration in coal and coalbed methane production. Since the gas sorption process in coal has an exothermic nature, temperature changes can inherently impact sorption and induced deformation behavior in coal. The current research aims to study the evolution of deformation behavior in terms of kinetics over time under isothermal (318 K) and non-isothermal (318→298 K) conditions for coal exposed to different gases (CO2, CH4, and He). The results indicate that sorption deformation kinetics are influenced by gas types, gas pressures, and coal composition inhomogeneity. Four linear strains measuring strain kinetics in various micro-regions on coal surfaces reveal heterogeneous behaviors linked to the distribution of macerals. Regarding the non-isothermal process, deformation kinetics display distinct patterns for the three gases. A temperature decrease causes sample shrinkage when exposed to CH4 and He, while swelling occurs with CO2 exposure, which may result from a combined effect of temperature change and differing sorption mechanisms of these gases in coal. Additionally, the temperature decrease leads to a phase state change in CO2, transitioning from supercritical to gas to liquid. The study shows continuous deformation kinetics, with no significant impact of the phase change on the deformation behavior observed.

CO2 Adsorption/Desorption, Induced Deformation Behavior, and Permeability Characteristics of Different Rank Coals: Application for CO2-Enhanced Coalbed Methane Recovery

CO₂ Adsorption/Desorption, Induced Deformation Behavior, and Permeability Characteristics of Different Rank Coals: Application for CO₂-Enhanced Coalbed Methane Recovery

N-rich Zr3N4 nanolayers-dependent superhard effect and fracture behavior in TiAlN/Zr3N4 nanomultilayer films

The TiAlN/Zr3N4 nanomultilayer films were successfully fabricated by alternatively inserting nitrogen-rich orthorhombic o-Zr3N4 monolayers onto TiAlN nanolayers via magnetron sputtering, and then the Zr3N4 layer thicknesses (lZr3N4)-dependent microstructure, hardness and deformation behavior was further explored. At a thin lZr3N4 of =1.1 nm, Zr3N4 nanolayers were forced to crystallize with a metastable cubic c-Zr3N4 pseudocrystal structure and form (111)-oriented c-TiAlN/c-Zr3N4 coherent interfaces with c-TiAlN sublayers, thereby achieving maximum H of 34.7 GPa yet superior toughness. For a thicker lZr3N4, Zr3N4 nanolayers gradually transformed from the pseudocrystal c-Zr3N4 to bulk-energy-stabilized o-Zr3N4; it destroyed the coherent growth and yielded fast drop in both H and fracture toughness. Furthermore, the indenter induced deformation behavior of the nanomultilayer with lZr3N4 = 4.2 nm was observed by transmission electron microscopy (TEM), thus indicating that severe plastic deformation in the nanomultilayer is primarily accommodated via the bending of nanolayers and formation of nanoscale longitudinal and lateral cracks rather than the formation of large-scale cracks because of crack deflections that can be attributed to layer interfaces.

Fatigue-Assisted Grain Growth in Al Alloys

Stress-assisted grain growth at room temperature is known for materials with nanocrystalline grains. For larger grain sizes, the grain growth usually takes place at higher homologous temperatures even under stress. Here we report, for the first time, significant grain growth at room temperature under fatigue loading in microcrystalline grains (≥10 μm) in Al 7075. We demonstrate that this grain growth at room temperature is similar to non-uniform grain growth due to grain rotation and coalescence rather than the thermally and the stress-assisted driven grain growth. We show that the grain growth is associated with the formation of a strong near-Cu {112}<111> texture component as a result of fatigue-assisted deformation. These changes in microstructural features (viz., grain size, grain orientations and texture) are fundamentally important in understanding the cyclic crack induced deformation behavior and for predicting the fatigue lifetime in structural materials.

A mechanistic model for anisotropic thermal strain behavior of soft mudrocks

Under drained heating, soft mudrocks can expand or contract depending on its mineralogy, composition, structure, stress history, and the imposed temperature. Previous research on the physics behind the thermally induced deformation behavior is limited. The impact of clay minerals on the overall anisotropic deformation behavior has not been quantitatively considered. In this study, a compositional thermal strain model is proposed to quantify the thermally induced deformation in soft mudrocks through a homogenization approach. The intrinsic fabric of soft mudrock was examined and considered in the model. Theoretically, thermally induced deformation in a soft mudrock is contributed by the expansion of solid minerals and interlayer bound water, the removal or dehydration of clay-bound water, and thermal plastic strain (grain rearrangement). The overall deformation of soft mudrocks is governed by the thermal deformation behavior of individual constituents and their interactions. The interactions among non-clay minerals and clay-water composites can be considered by applying a structural state coefficient. The proposed thermal strain model was validated by a series of experimental results using reconstituted and natural soft mudrock samples with different clay fractions. The results indicate that soft mudrocks with a structural state of clay matrix-supported are on the risk of having thermal contraction behavior which comes from clay dehydration or thermal plastic strain. The oriented fabric in soft mudrocks contributes to the anisotropy in thermal strains. The proposed thermal strain model can be applied to estimate critical parameters in phenomenon-based thermal elastic-plastic models for constitutive modeling.

Scratch induced deformation behavior of hafnium based bulk metallic glass at multiple load scales

The scratch induced deformation behavior of Hafnium based bulk metallic glass (BMG) at micro- and macro-load scales is reported in this study. The micro-scratch deals with a normal load range of 1000–8000μN, whereas the macro-scale scratches are made with a normal load reaching up to 5N. Increase in the load beyond 2000μN changes the deformation mechanism from plowing to fracture and chipping. The plastic strain is mostly accommodated by shear band formation with a significant amount of free volume generation. A change in the strain rate helps in the nucleation of shear bands and prevents fracture and chipping in the case of micro-scratches made at ramp loading as compared to constant load. Higher strain rate and heat generation in the track causes increased strain hardening in macro-scratch, which could be attributed to increased probability of nano-crystallization. Complex shear band structure is evolved during scratching, which is attributed to the mixed type of loading, consisting of compressive normal load and lateral shear load across scratch-track.

Enhanced work-hardening behavior and mechanical properties in ultrafine-grained steels with large-fractioned metastable austenite

Ultrafine-grained duplex manganese-bearing steels fabricated by quenching and annealing demonstrated excellent combinations of tensile elongation of 31–44% and tensile strength of 1–1.5 GPa and a three-stage work-hardening behavior. Their enhanced mechanical properties and work-hardening behavior were explained by their dynamic composition due to the strain induced phase transformation from large-fractioned austenite (>30%). It was suggested that the austenite volume fraction and its mechanical stability is the key to understand the phase transformation induced deformation behavior.

Nanoscale deformation measurement of microscale interconnection assemblies by a digitalimage correlation technique

The continuous miniaturization of microelectronic devices and interconnections demandmore and more experimental strain/stress analysis of micro- and nanoscale components formaterial characterization and structure reliability analysis. The digital image correlation(DIC) technique, with the aid of scanning probe microscopes, has become a verypromising tool to meet this demand. In this study, an atomic force microscope(AFM) was used to scan and digitally image micro-interconnection assemblies in amicro-thermoelectric cooler. AFM images of the scan region of interest were obtainedseparately when the microelectronic device was operated before and after thecooling and heating stages. The AFM images were then used to obtain the in-planedeformation fields in the observed region of the micro-assembly. AFM image correlationis performed for nanoscale deformation analysis using the authors’ AFM–DICprogram. The results show that the observed region was subjected to cyclic strainswhen the device worked between its cooling and heating stages, and cyclic strainin the vertical direction was found to be a significant deformation mode. Thethermally induced deformation behavior of the micro-assembly device was modeled byfinite element analysis (FEA). Both thermal-electric analysis and thermal stressanalysis were conducted on a 3D finite element model of the device. It is shown thatthe experimental results were able to validate the finite element analysis results.

Modeling of magnetostriction in particulate composite materials

By combining a magnetostrictive material with a polymer or a metal, the magnetostrictive composites can have a reasonably large magnetostriction response for various sensor and actuator applications. In this paper, a relatively simple model for studying the magnetostrictively induced deformation behavior of magnetostrictive composites is presented. For illustrative purposes, we calculate the magnetostriction responses of composites containing Terfenol-D and nickel. Through numerical calculation, we have obtained the macroscopic longitudinal strains parallel to the applied magnetic field for Terfenol-D/glass composite and both longitudinal and transverse strains for the nickel/epoxy composite. Comparison with experimental data for both material systems shows our model is applicable up to very high volume fraction of magnetostrictive inclusions.

Substrate Effects on the Micro/Nanomechanical Properties of TiN Coatings

Nanoindentation and nanoscratch tests were performed for titanium nitride (TiN) coatings on different tool steel substrates to investigate the indentation/scratch induced deformation behavior of the coatings and the adhesion of the coating–substrate interfaces and their tribological property. In this work, TiN coatings with a thickness of about 500 nm were grown on GT35, 9Cr18 and 40CrNiMo steels using vacuum magnetic-filtering arc plasma deposition. In the nanoindentation tests, the hardness and modulus curves for TiN/GT35 reduced the slowest around the film thickness 500 nm with the increase of indentation depth, followed by TiN/9Cr18 and TiN/40CrNiMo. Improving adhesion properties of coating and substrate can decrease the differences of internal stress field. The scratch tests showed that the scratch response was controlled by plastic deformation in the substrate. The substrate plays an important role in determining the mechanical properties and wear resistance of such coatings. TiN/GT35 exhibited the best load-carrying capacity and scratch/wear resistance. As a consequence, GT35 is the best substrate for TiN coatings of the substrate materials tested.

Evaluation of mechanical properties of ceramic coatings on a metal substrate

Nanoindentation and tensile tests were performed for TiN coatings on a stainless steel substrate to investigate the indentation induced deformation behavior of the coatings and the adhesion of the coating–substrate interface. Load–displacement curves show the transition of plastic deformation state from coating only to coating–substrate composite in a penetration depth of 1/10 of the coating thickness, which is approximately two times smaller than that of metal coatings. We employed two specimens with different interface characteristics for the evaluation of the adhesion. The tensile test can clearly detect the difference by the analysis of statistics of extremes for the maximum crack spacing, while the indentation results show no difference, suggesting that the tensile test is superior in detecting the adhesion of the coating–substrate interface.