Compressive Deformation Behavior Research Articles

Research on predicting the thermocompression deformation behavior of Mg-Li matrix composite using machine learning and traditional techniques

Artificial intelligence and machine learning (ML) technologies have emerged as powerful tools for analyzing the thermal compression deformation behavior of metal matrix composites, offering significant potential to optimize their plastic deformation processing techniques. In this study, the Al3La/LAZ532 composite based on in-situ self-reaction technology was successfully prepared by adding La2O3 particles. Then, the thermal compression flow behavior of the as-cast composite was comparatively researched using a traditional Arrhenius model and advanced machine learning methods (Linear Regression, AdaBoost, Random Forest, and XGBoost). The flow stresses were predicted under various thermal operating conditions, and the performance of all models was assessed using root mean square error (RMSE), coefficient of determination (R2) and mean absolute error (MAE). Analysis shows that the Random Forest model outperforms traditional models and other ML methods in predictive accuracy, achieving an R2 of 0.97, an MAE of 5.8, and an RMSE of 7.07. Additionally, the stable hot working zone for the composite at 300 °C and a strain rate of 0.001∼0.01 s⁻1 can be identified by combining the microscopic structure with the macroscopic hot working map. This zone is characterized by a uniformly distributed, fine-grained structure with high levels of dynamic recrystallization (DRX). The texture with the <0001> axis of the grains aligned parallel to the compression direction (CD) is formed in the thermally deformed microstructure, and the DRX mechanism is discontinuous dynamic recrystallization (DDRX).

Compressive Mechanical Properties and Energy Absorption of Cubic Spherical Hollow Cellular Material Based on the Rod and Curved Surface Structure

Cellular materials, such as lattices and honeycombs, were widely used for structural protection owing to their excellent mechanical properties. By combining the excellent characteristics of lattice and honeycomb curved surface structures, this study designed a cell called Cubic Spherical Hollow (CSH), which had the advantages of orthogonal isotropy and better spatial connectivity. Inspired by the micro-structural arrangement of bamboo fiber and conch shell, we designed the new CSH cellular materials through the interlayer offset strategy. Then, the effects of interlayer offset on the mechanical properties and compression deformation behavior were explored experimentally and simulatively. Compared with other cellular materials, CSH cellular materials exhibited excellent mechanical properties with higher specific strength and specific modulus. The arrangement offsets of the CSH cells between different layers led to a change in the deformation mechanism from a rod’s compressive mode to a combination of a rod’s compressive mode and curved surface’s bending mode. The initial peak stress and plateau stress decreased with the increased arrangement offsets of the CSH since the extruded protrusions of the structure filled the holes and reduced the lateral expansion behavior of the material in the pressurized environment. This phenomenon also reduced the transverse expansion and prevented the sudden change in stress in the constrained space, indicating that the structural deformation was stable and had excellent cushioning and energy absorption properties. In this study, the cellular material design strategy opens a new avenue for energy absorption.

Effect of tungsten-particle size on the room temperature compressive deformation behaviour of Zr55Cu30Al10Ni5 amorphous alloy

W-particle-reinforced Zr-based amorphous composites (Wp/Zr55Cu30Al10Ni5) with a W-particle volume fraction of 50 % and W-particle sizes of 30, 75 and 250 μm were prepared through spark plasma sintering. The effects of different W-particle sizes on the quasi-static and dynamic compressive behaviours of the composites were investigated using a scanning electron microscopy/energy-dispersive X-ray spectroscopy instrument, a universal testing machine and the split-Hopkinson pressure bar. The results showed that the addition of W particles considerably enhanced the strength and ductility of the amorphous composites. Under quasi-static compression, the compressive strength of the W-particle-reinforced Zr-based amorphous composites increased as the W-particle size decreased; the fracture strain also increased accordingly. At a W-particle size of 30 μm, the composite achieved a maximum compressive strength of 1905 MPa and a maximum strain of 18.4 %. Under dynamic-compression conditions, the W-particle size was inversely proportional to the dynamic-compression strength of the material, with 3074 MPa obtained as the maximum strength. An analysis of the fracture morphology of the amorphous composites reveals that the fracture mode transitions from shear fracture to a mixed mode dominated by the W particles, a process involving interface debonding, cleavage fracture and ductile fracture.

Experiment and enhancement of compressive strength perpendicular to the grain of inorganic-bonded bamboo composite

ABSTRACT The inorganic-bonded bamboo composite (InorgBam) is a novel type of bamboo-based composite: a combination of magnesium oxysulfide inorganic adhesive and bamboo fiber strips, which exhibits significant material anisotropic characteristics with compressive strength perpendicular-to-grain typically lower than that of parallel-to-grain. The impact of loading form including full-area compression, middle and end local compression on strength perpendicular-to-grain was examined. The enhancement of compressive strength perpendicular to the grain using the glued-in rods (GiRs) method was tested. A prediction formula for ultimate load-carrying capacity perpendicular to the grain of enhanced InorgBam material was proposed considering the influence of load form and depths of GiRs. Results indicate that the full-area compression perpendicular to the grain exhibits a higher load-carrying capacity compared to the middle and end local compression. The GiRs method significantly enhances the compression strength and deformation behavior perpendicular to the grain of InorgBam material. The compressive load-carrying capacity and elastic modulus of the enhanced specimens can be increased by 83% and 157%, respectively. The prediction formula based on the replacement ratio of GiRs can well predict the strength of enhanced specimens.

Effect of precipitation phase on the flow behavior of a nickel-based superalloy during compressive deformation

Nickel-based superalloys have become indispensable in micro-forming processes owing to their outstanding mechanical properties. The size effect significantly impacts the formability of components at the mesoscopic scale, resulting in compression deformation behaviors distinct from those observed at the macroscopic scale. The classical Hall-Petch formula can hardly express this phenomenon precisely. This study conducted compression tests of a nickel-based superalloy at the mesoscopic scale, exploring the role of the feature size (specifically, the ratio of sample diameter to grain size, D/d) and the precipitation phase on the plastic deformation behavior. The results show that increasing feature size of samples as well as particle size and volume fraction of γ′ and γʺ phases enhance the flow stress of the superalloy. When the feature size exceeds 8.6, the flow stress decreases with decreasing feature size. However, when the feature size is below 8.6, the flow stress increases with decreasing feature size. A model is proposed to comprehensively explain the size effect and the precipitation phase on compressive flow stress. The surfaces of samples experience inhomogeneous deformation during compressive deformation. The trend towards inhomogeneous deformation has become more pronounced as feature size decreases. Furthermore, the increase in particle size and volume fracture of γ′ and γʺ phases limits the inhomogeneous deformation of the sample surface.

Effects of the Space Holder Shape on the Pore Structure and Mechanical Properties of Porous Cu with a Wide Porosity Range.

Porous copper (Cu), with varying porosities, has been made using carbamide as a space holder through the powder metallurgy route. Two shapes of carbamide particles were used, (i) needlelike and (ii) spherical, in order to investigate the effect of the space holder shape on the pore structure and mechanical properties of porous Cu. The compressive deformation behavior of porous Cu was studied under a compression test. The pores' structural characteristics and mechanical properties of the porous Cu varied significantly with the shape of the space holder. Although the effect of the space holder shape on the porosity was not regular, the effect on the mechanical properties was regular. The stress increased monotonically with the increase in the strain, and strain hardening occurred at the plastic yield stage. The elastic modulus and yield strength followed the power law, with the relative density irrespective of the space holder shape. The empirical constants associated with different empirically developed power law relations were different, according to the shape of space holder. A quantitative relationship between the elastic modulus and yield strength and the spacer content was obtained to control the mechanical properties of the present porous Cu or other porous metals and metal foams using the well-known space holder method.

Effect of hydrogen content on the high-temperature compressive deformation behavior and microstructure evolution of TC17 alloy

Thermo-hydrogen process (THP) has been an important research direction of the titanium alloy heat treatment process. However, the effect of THP on the thermal deformation behavior and microstructure evolution of TC17 alloy during hot compression has not been investigated. In this study, a series of isothermal compression experiments were carried out on hydrogenated TC17 alloy specimens in the temperature range covering the α+β phase region and β phase region of TC17 alloys with different hydrogen contents, to investigate the effect of hydrogen on the high-temperature flow behavior and microstructure evolution. The results show that the primary α phase of the hydrogenated TC17 alloy is significantly reduced. Observing the XRD pattern, the substitutional solution effect of hydrogen causes the β phase lattice to expand, resulting in a shift of the β phase toward a small angle as the hydrogen content increases. The flow stress shows a tendency to decrease and then increase with increasing hydrogen content. This is attributed to the softening effect of hydrogen on the α phase and the hardening effect on the β phase. This also leads to the deformation activation energy showing the same trend. When the hydrogen content increases to 0.4 wt%, the activation energy decreases to the lowest point by about 24 %. Finally, the appropriate hydrogen concentration can effectively reduce the destabilization region in the hot working map and expand the processing window of TC17 alloy.

Spatial reconstruction, microstructure-based modeling of compressive deformation behavior, and prediction of mechanical properties in lightweight Al-based entropy alloys

Lightweight Al-based entropy alloys are newly emerged materials with promising potential for structural applications; however, their modeling and strengthening prediction require further exploration. In this study, the spatial distributions of various phases in three Al-based entropy alloys were investigated. A closely interconnected intermetallic compound (IC) network comprising Al2Cu and Al45Cr7 phases was identified. Finite element (FE) modeling was conducted based on the reconstructed three-dimensional microstructure to simulate compressive deformation behavior. The IC network served as the main stress bearer during deformation. Thin sections in the Al2Cu network were the weak sites where stress concentration and damage first occurred. However, the breakage of this limited region contributes to relatively coordinated deformation and extended plasticity. The breakage of large particles accounts for the final alloy failure. The results of the FE model were compared with the experimentally measured stress–strain behavior and mechanical properties, showing very good agreement. Given the non-uniform distribution of strain and stress during deformation, a strengthening model, merging the Voigt and Reuss models, was also developed to predict the mechanical properties of Al-based entropy alloys with the aim of facilitating Al-based entropy alloy development.

Density dependent constitutive model for Bi-2212 powder compression deformation

Bi-2212 HTS materials are fabricated into multi-filamentary wires via powder-in-tube (PIT) method followed by proper heat treatment to obtain superconductivity, but how to predict the large compression deformation behaviors of the Bi-2212 powder is critical to design the processing of the Bi-2212 HTS wire. Drucker Prager/Cap (DPC) model was the most commonly used model for powders including Bi-2212 with soil-like mechanical behavior to consider its shear failure as well as hydrostatic compression. However, the parameters for DPC Cap evolve with densities change and the original model is inadequate to precisely describe the densification process of Bi-2212 powder with large strain. In this study, the modified DPC model with density dependent parameters was introduced for Bi-2212 powder compressions by measuring the failure strength and hydrostatic compressive behavior under different density states. The DPC yield surface was plotted with an evolution trend of non-linear outward expansion with density increased. FEM model of uniaxial compression based on the as-introduced model was built with subroutine VUSDFLD applied. The distribution of Mises stress and relative density were analyzed. The axial stress-density curve for FEM and experimental results were normalized and quantitively evaluated by Mean Square Error (MSE). The introduced model shows good convergence and could match the experimental results well with normalized MSE of 0.000207 and Root Mean Square Error (RMSE) of 0.0144, indicating the mean error percentage of 1.44%. The model introduced in this article provides supports toward large strain deformation simulation of Bi-2212 powder.

Orientation-dependent deformation behaviors of β single crystal micropillars in a metastable β titanium alloy

The compressive deformation behaviors were investigated in metastable β Ti–7Mo–3Al–3Cr–3Nb alloy single crystal micropillars oriented to [011]β and [001]β. The study demonstrates that the metastable β titanium single crystal oriented to [001]β exhibits nonlinear elastic behavior with hysteresis, which is attributed to reverse β to α″ transformation. Furthermore, the yield strength of the single crystal oriented to [011]β is almost twice as of the single crystal oriented to [001]β, which is influenced by the different roles of ωath in both pillars due to differences in shear modulus G, in addition to being determined by the deformation mechanism at yielding. The continuous impedance to dislocation motion of ω and α″ phase in the pillar oriented to [011]β leads to a stable plastic flow behavior, but reverse β to ω phase transformation facilitating the formation of massive SIMα″ results in a sudden strain burst in the pillar oriented to [001]β. Finally, we find that the pillar oriented to [011]β is dominated by dislocation slip but SIMα″ occupies a dominant position in the pillar oriented to [001]β in the early deformation stage, which is same as predicted based on the martensitic transformation theory in metastable β titanium alloys.

Effect of Reinforcement on Micro Structural and Compressive Deformation Behavior on Closed Cell AA7075 Aluminium Foam

Effect of Reinforcement on Micro Structural and Compressive Deformation Behavior on Closed Cell AA7075 Aluminium Foam

Study of flow stress in Mg-Gd-Y-Nd-Zr alloys based on IWOA-BPNN model

This study investigates the compression deformation behavior of an Mg-Gd-Y-Nd-Zr alloy at temperatures ranging from 293 K to 573 K and strain rates ranging from 293K to 573K and strain rates ranging from 1000 s−1 to 2100 s−1 using a split Hopkinson pressure bar. A modified Johnson-Cook (JC) constitutive model and a backpropagation neural network (BPNN) model based on the improved whale optimization algorithm (IWOA) are established. Four statistical metrics, including correlation coefficient (R), mean absolute error (MAE), mean absolute percentage error (MAPE), and root mean square error (RMSE), are employed to evaluate the predictive accuracy of the two models. The findings indicate that the flow stress of the alloy is sensitive to strain, strain rate, and temperature. Increasing strain and strain rate or decreasing deformation temperature results in higher flow stress. Error calculations revealed that the modified Johnson-Cook constitutive model has an R of 0.98731, a MAPE of 7.3653%, a MAE of 19.6305 MPa, and a RMSE of 26.5704 MPa. In contrast, the model established using the IWOA-BPNN has an R of 0.99996, a MAPE of 0.58894%, a MAE of 1.2671 MPa, and a RMSE of 1.7709 MPa. The IWOA-BPNN model demonstrates higher accuracy and accurately predicts the flow stress of the alloy.

Influence of power dissipation value and deformation activation energy on recrystallization in compression deformation behavior of Mg-Li-Zn-Y alloy

The thermal compression deformation behavior of Mg-6Li-11Zn-2.5Y alloy was systematically investigated by using the isothermal hot compression tests using the Gleeble-3500 thermal mechanical physical simulation system with the conditions of the temperature of 513–593 K and the strain rate of 0.01–10 s−1. The constitutive model and thermal processing map were established. The variation pattern of the unstable region under different strains was analyzed and the safe processing region was determined. The influence of different power dissipation values and deformation activation energies on the dynamic recrystallization mechanism was clarified. The results demonstrate that the deformation activation energy is 156.08 kJ/mol. The unstable region gradually expands from the low temperature and low strain region to the high temperature and high strain region with the strain increasing. In the unstable region, adiabatic shear band pear in α-Mg phase, of which the main reason is the poor processing formability in the unstable region. The dominant nucleation mechanism is discontinuous dynamic recrystallization under the conditions of high power dissipation and low deformation activation energy. While, under the conditions of low power dissipation and high deformation activation energy, the nucleation mechanism is mainly driven by the particle stimulated nucleation.

Combined Effect of Particle Reinforcement and T6 Heat Treatment on the Compressive Deformation Behavior of an A357 Aluminum Alloy at Room Temperature and at 350 °C

Solid state sintering of cast aluminum powders by resistance heating sintering (RHS), also known as spark plasma sintering or field-assisted sintering technique, creates a very fine microstructure in the bulk material. This leads to high performance material properties with an improved strength and ductility compared to conventional production routes of the same alloys. In this study, the mechanical behavior of an RHS-sintered age-hardenable A357 (AlSi7Mg0.6) cast alloy and a SiCp/A357 aluminum matrix composite (AMC) was investigated. Aiming for high strength and good wear behavior in tribological applications, the AMC was reinforced with a high particle content (35 vol.%) of a coarse particle fraction (d50 = 21 µm). Afterwards, separated and combined effects of particle reinforcement and heat treatment were studied under compressive load both at room temperature and at 350 °C. At room temperature compression, the strengthening effect of precipitation hardening was about twice as high as that for the particle reinforcement, despite the high particle content. At elevated temperatures, the compressive deformation behavior was characterized by simultaneously occurring temperature-activated recovery, recrystallisation and precipitation processes. The occurrence and interaction of these processes was significantly affected by the initial material condition. Moreover, a rearrangement of the SiC reinforcement particles was detected after hot deformation. This rearrangement lead to a homogenized dispersion of the reinforcement phase without considerable particle fragmentation, which offers the potential for secondary thermo-mechanical processing of highly reinforced AMCs.

Effect of carbon nanotubes content on compressive properties and deformation behaviors of aluminum matrix composite foams

The incorporation of nano carbon reinforcement is a useful strategy to broaden the engineering applications of metal foams. In this work, carbon nanotubes (CNTs) reinforced aluminum (Al) matrix composite foams (CNTs/Al composite foams) with different CNTs content are prepared by combining ball-milling technique with powder metallurgy method. The result shows that the appropriate content of CNTs can reduce the pore size, improve the circularity, and enhance the compressive properties. Especially, the 1.0 wt% CNTs/Al composite foams possess the optimal compressive properties of yield stress (7.90 MPa), plateau stress (8.75 MPa) and energy absorption capacity (5.19 MJ/m3), which have an enhancement of 23.24%, 98.41% and 84.70%, respectively. Composite foams undergo shear deformation throughout the quasi-static compression process, and the failure mode performs as the brittle mode combined with ductile mode. Meanwhile, the incorporation of CNTs can contribute to the inhomogeneous distribution of the Si phase, provide more nucleation sites, and significantly refine the pore size. It is confirmed that the CNTs in composite foams contribute the grain refinement and the formation of micro stacking faults, making the mechanical properties of CNTs/Al composite foams outperform the counterpart of Al-Si foams. Moreover, due to the weak interfacial reaction, the low content of aluminum carbide is formed, which can promote the load transfer between CNTs and Al. The present finding provides a theoretical and practical design strategy to the future preparation of CNTs/Al composite foams.

Study on hot compressive deformation behavior and microstructure evolution of G13Cr4Mo4Ni4V steel

To solve the problem of poor uniformity of microstructure of high alloy bearing steel G13Cr4Mo4Ni4V after rolling, the deformation behavior of the steel and its effect on the microstructure evolution was studied systematically. Gleeble-3800 thermo-mechanical simulator was used for precise control of deformation temperature ranging from 1000 to 1200 °C and deformation rate 0.01–10 s−1. Based on modified stress and strain curves by temperature and friction, the processing map of tested steel was drawn. Electron backscatter diffraction (EBSD) and transmission electron microscope (TEM) were used to analyze the typical microstructure and carbide properties of different hot working domains respectively. The results showed the processing map could be divided into four regions: domain A 1000–1150 °C, 0.1–10 s−1; B 1000–1100 °C, 0.01–0.1 s−1; C 1100–1150 °C, 0.01–0.1 s−1 and D 1150–1200 °C, 1–10 s−1. Domain A was characterized by incomplete dynamic recrystallization (DRX) which included fine recrystallized grains and elongated deformed grains, whose softening mechanism was mainly discontinuous DRX (dDRX) and limited DRV and continuous DRX (cDRV) related to the ferrites and carbides. For domain B, the deformed grains gradually disappear with temperature rising, instead serrated grains appear with dDRX as dominating softening mechanism. A large number of carbides hinder DRX at 1000 °C with low temperature. With the increase of temperature, carbides dissolve and DRX degree increases. Grain coarsening is obvious because of high deformation temperature and low strain rate in domain C, although the nanoscale MC type carbides prevent recrystallization grain coarsening to some extent. Completely DRX resulted in uniform and fine with defect-free deformation microstructure in domain D, whose volume fraction of recrystallization reached up to 0.96 according to EBSD results. By considering the uniformity of microstructure and the distribution of carbide comprehensively, domain D is an ideal region for hot working.

Microstructure and compressive deformation behavior of W-Ni3Al-Co model alloys by two-step sintering

The regulation of microstructure can improve the mechanical properties of tungsten alloys. To regulate the microstructure, the W-Ni3Al-Co alloys with different Ni3Al/Co ratios were prepared using a two-step sintering method, and the microstructure and compressive deformation behavior were investigated. The results showed that the particle sizes of the W-rich phase in the network structure were refined with the increase of the Ni3Al/Co ratio, and a large fraction of twin boundaries were detected in the adhesive phase. The compressive deformation behavior of a W-7Ni3Al-3Co alloy with excellent compressive properties was investigated by the EBSD technique. The results demonstrated that twins in the FCC binder phase hindered the stress concentration in the binder phase and at the interface of the W/binder phases through twin-dislocation interactions. The W network structure underwent the uniform global deformation that restricted grain boundary sliding during deformation and prevented crack extension and consolidation. Twins in the binder phase and the W network structure were both important factors in improving the compressive properties of W-Ni3Al-Co alloys.

Compression performance of 3D-printed thermoplastic auxetic structures

The influence of lattice structural design on the mechanical property has been abundantly investigated, however, the effect of material on the load-carrying performance and energy absorption was seldom studied. In the current work, the auxetic structures fabricated using four materials including polyamide (PA), carbon fiber (CF) reinforced PA (PA/CF), polyether ether ketone (PEEK) and PEEK/CF were 3D-printed, and the compression performance and deformation behavior were compared and explored. The results showed that the deformation mode of auxetic structure were similar, which was not dependent on the material type. However, the compressive strength and modulus of the auxetic structure showed strong dependence on the material properties. Besides, PA and PA/CF auxetic structures displayed better rebound behavior after compression, which was perhaps attributed to the good resilience of PA resin. Therefore, mathematical equations were utilized to predict the compressive property based on the material parameters, showing a good agreement. On the other hand, the simulation of compression process was established and conducted, which confirmed the deformation process as experimental presented. The rebound behavior was further predicted by a loading-releasing cycle with different compression strains. Accordingly, the compression parameters showed great relations with material parameters but little effect on the deformation behavior.

Enhancing the bioactivity and ductility of bulk metallic glass by introducing Fe to construct semi-degradable biomaterial

Porous Ti–Zr–Cu–Pd–Sn bulk metallic glass (BMG) produced by Spark Plasma Sintering (SPS) in our previous work demonstrates bone-like mechanical properties, effectively mitigating the issue of stress shielding within the implant. Nevertheless, concerns persist regarding the BMG's brittleness and its lack of bioactivity, both of which pose concealed risks in practical applications. In light of these challenges, a semi-degradable biomaterial, the MG-Fe composites, has been meticulously crafted via SPS in this work. The incorporation of ductile Fe phase in the MG matrix significantly enhances its plasticity. Moreover, the degradation of Fe results in the deposition of Ca–P compounds, imbuing the MG-Fe composites with a degree of bioactivity. Furthermore, by introducing a gradient porous structure, researchers have managed to fine-tune the mechanical properties of the MG-Fe composites. This innovative design imparts plastic and ductile compression deformation behavior to the gradient porous MG-Fe composites, offering a potential solution to the issue of brittle fracture behavior observed in conventional brittle BMGs. In addition, the introduction of the gradient porous structure serves to further accelerate the degradation rate of Fe. This advancement holds the potential to strike a dynamic balance with the growth rate of human bone, further elevating the bioactivity of the MG-Fe composites.

Hot deformation behavior, superplasticity and microstructure evolution of a new hot isostatic pressed nickel-based superalloy

The new hot isostatically pressed (HIP) superalloy has demonstrated remarkable superplastic characteristics, as evidenced by studying the compression and tensile deformation behavior. To identify the superplastic deformation zone, the instability regions at various strain variables were overlaid onto the strain rate sensitivity index (m) distribution map at a strain of 0.6, resulting in the acquisition of a new hot working map. The tensile test results showed that under the conditions of 1080 °C-10−2.5 s−1 (0.35 < m < 0.43) and 1030 °C-10−3 s−1 (0.66 < m < 0.74) which located in the superplastic deformation zone in the new hot working map, the new HIPed superalloy exhibited superplasticity, and the elongation was 395 % and 410 %, respectively. Considering the hot working map and the microstructure evolution, the suitable hot working window was further optimized to be 1030–1080 °C and 0.001–0.005 s−1. At high strain rate and low temperature conditions, continuous dynamic recrystallization (CDRX) was the primary mechanism for dynamic recrystallization (DRX), while with the gradual decrease of strain rate, discontinuous dynamic recrystallization (DDRX) tended to occur and dominate the process. DDRX dominated under high temperature deformation condition.