The Effect of ZnO Addition on Microstructure, Phase and Color Developments of Copper Reduction Glaze

In this research, the effects of Zn on microstructure and color developments of the copper reduction glaze were investigated. Structural and colorimetric characteristics of the glaze surface are examined by X-ray diffraction, scanning electron microscope (SEM) equipped with electron dispersive spectroscopy (EDS) and Telespectrophotometery. Results indicate in samples consisted of more than 7 % of zinc amount, crystalline structures containing Willemite and synthesized copper. XRD indicate that, 14 wt% of zinc oxide is enough to form Willemite. In all samples, duration of process was sufficient to form the metallic particles. SEM images confirm presence of copper nanosphere-laths of Willemite and surrounding glaze

The Effect of ZnO Addition on Microstructure, Phase and Color Developments of Copper Reduction Glaze

In this research, the effects of Zn on microstructure and color developments of the copper reduction glaze were investigated. Structural and colorimetric characteristics of the glaze surface are examined by X-ray diffraction, scanning electron microscope (SEM) equipped with electron dispersive spectroscopy (EDS) and Telespectrophotometery. Results indicate in samples consisted of more than 7 % of zinc amount, crystalline structures containing Willemite and synthesized copper. XRD indicate that, 14 wt% of zinc oxide is enough to form Willemite. In all samples, duration of process was sufficient to form the metallic particles. SEM images confirm presence of copper nanosphere-laths of Willemite and surrounding glaze

A novel approach to determine residual stress field during FSW of AZ91 Mg alloy using combined smoothed particle hydrodynamics/neuro-fuzzy computations and ultrasonic testing

The faults in welding design and process every so often yield defective parts during friction stir welding (FSW). The development of numerical approaches including the finite element method (FEM) provides a way to draw a process paradigm before any physical implementation. It is not practical to simulate all possible designs to identify the optimal FSW practice due to the inefficiency associated with concurrent modeling of material flow and heat dissipation throughout the FSW. This study intends to develop a computational workflow based on the mesh-free FEM framework named smoothed particle hydrodynamics (SPH) which was integrated with adaptive neuro-fuzzy inference system (ANFIS) to evaluate the residual stress in the FSW process. An integrated SPH and ANFIS methodology was established and the well-trained ANIS was then used to predict how the FSW process depends on its parameters. To verify the SPH calculation, an itemized FSW case was performed on AZ91 Mg alloy and the induced residual stress was measured by ultrasonic testing. The suggested methodology can efficiently predict the residual stress distribution throughout friction stir welding of AZ91 alloy.</p

Quantitative kinetic analysis of γ′ precipitate evolution in a Co–Al–W superalloy during aging heat treatment

In this research, the effect of aging-heat treatment on evolution of γ′-precipitates in the Co–Al–W-based superalloy was studied. For this purpose, solution heat treatment was applied followed by water-quenching and then, aging different cycles were carried out at four temperatures of 720, 780, 840 and 900 °C for different holding time (1–48 h). The electron microscope micrographs showed that increasing size of γ′ particles happens with more holding time; while volume fraction stays approximately constant at 0.72. In addition, the γ-γ′ lattice mismatch, as positive values, increased with holding time increase due to simultaneous γ′ shape adaptation. While the γ′ morphology variation was seen to change from spherical to semi-cubic and cubic; the L- and stretched-shapes of γ′-particles with concurrent split of the coarse particles was detected by coarsening, coalescence and splitting phenomena, respectively. The proposed mechanisms for such microstructural evolution were interpreted based on n value as the power term in kinetics equation. As such, the γ′-particles diffusion across the γ/γ′ interface (n∼2), volume-diffusion (n∼3) and coalescence/splitting (n∼7) are key controlled processes at different aging temperature ranges. The characteristics of γ′-precipitates was discussed in detail based on total energy concept in terms of surface (Esur.), elastic strain (Estr..) and interactions of elastic (Eint.) energies and hence, a phenomenological model was proposed for evolution of γ′-particles. Modeling based a physical model and analysis of microhardness experimental revealed that the desired radius of γ′ phase should be between 80 nm and 90 nm respectively; and the optimized aging condition is estimated to be done at 840 °C for 36 h

Modeling of hot deformation behavior and prediction of flow stress in a magnesium alloy using constitutive equation and artificial neural network (ANN) model

The aim of the present study was to investigate the modeling and prediction of the high temperature flow characteristics of a cast magnesium (Mg–Al–Ca) alloy by both constitutive equation and ANN model. Toward this end, hot compression experiments were performed in 250–450 °C and in strain rates of 0.001–1 s−1. The true stress of alloy was first and foremost described by the hyperbolic sine function in an Arrhenius-type of constitutive equation taking the effects of strain, strain rate and temperature into account. Predictions indicated that unlike low strain rates and high temperature with dominant DRX activation, in relatively high strain rate and low temperature values, the precision of the models become decreased due to activation of twinning phenomenon. At that moment and for a better evaluation of twinning effect during deformation, a feed-forward back propagation ANN was developed to study the flow behavior of the investigated alloy. Then, the performance of the two suggested models has been assessed using a statistical criterion. The comparative assessment of the gained results specifies that the well-trained ANN is much more precise and accurate than the constitutive equations in predicting the hot flow behavior. Keywords: Hot deformation, Magnesium alloy, Modeling, Twinning, Hyperbolic sine equation, ANN mode

Finite element simulation and experimental investigation of hot forming cold die quenching and equal channel angular pressing of AA2024 aluminum alloy

The present study investigates the variations in the microstructure and mechanical properties of AA2024 aluminum alloy as a consequence of thermal and strain gradient in combined hot forming cold die quenching (HFQ) and equal channel angular pressing (ECAP) method. Solution-treated AA2024 aluminum alloy was HFQ–ECAPed for five passes of deformation and 3D simulations plus microstructural evolutions, and mechanical properties over the thickness of the sample were investigated. Furthermore, after each ECAP pass, intermediate solution treatment was applied, and a group of specimens was subjected to aging treatment following the deformation. 3D simulations illustrated strain uniformity by increasing the number of deformation passes with its maximum uniformity after four passes. Microstructural observations demonstrated evident grain refinement in successive passes, which were higher in the central and top parts of the sample than in the lower area. Also, a high quantity of shear bands occurred in the workpiece after the first ECAP pass. However, shear banding was deducted in the consecutive passes of deformation and intermediate solutionizing. Preferable properties in central regions were seen comparing tensile properties in surface area and central parts. Besides, the microhardness test resulted in more uniform outcomes by enhancement in the number of ECAP passes. Hardness variations showed an increase in average hardness after the first pass of deformation (compared to the annealed condition (Baghbani Barenji et al. in J Mater Res Technol 9:1683–1697, 2020) and then a negligible decrease in the following two passes. The hardness quantities again increased in the fourth pass and then dramatically decreased after the fifth pass due to the partial decomposition of the solid solution. Besides, due to strain distribution, hardness values illustrate the maximum and minimum amount in the uppermost and lowermost areas, respectively. The overall conclusions of this article presented mechanical similarities in the surface and inner parts of the material

Process Control Strategies for Dual-Phase Steel Manufacturing Using ANN and ANFIS

In this research, a comprehensive soft computational approach is presented for the analysis of the influencing parameters on manufacturing of dual-phase steels. A set of experimental data have been gathered to obtain the initial database used for the training and testing of both artificial neural networks (ANN) and adaptive neuro-fuzzy inference system (ANFIS). The parameters used in the strategy were intercritical annealing temperature, carbon content, and holding time which gives off martensite percentage as an output. A fraction of the data set was chosen to train both ANN and ANFIS, and the rest was put into practice to authenticate the act of the trained networks while seeing unseen data. To compare the obtained results, coefficient of determination and root mean squared error indexes were chosen. Using artificial intelligence methods, it is not necessary to consider and establish a preliminary mathematical model and formulate its affecting parameters on its definition. In conclusion, the martensite percentages corresponding to the manufacturing parameters can be determined prior to a production using these controlling algorithms. Although the results acquired from both ANN and ANFIS are very encouraging, the proposed ANFIS has enhanced performance over the ANN and takes better effect on cost-reduction profit

Microstructure and long-term stability of Ni–YSZ anode supported fuel cells: a review

Nickel–yttria stabilized zirconia (Ni–YSZ) cermet is the most commonly used anode in solid oxide fuel cells (SOFCs). The current article provides an insight into parameters which affect cell performance and stability by reviewing and discussing the related publications in this field. Understanding the parameters which affect the microstructure of Ni–YSZ such as grain size (Leng et al 2003 J. Power Sources 117 26–34) and ratio of Ni to YSZ, volume fraction of porosity, pore size and its distribution, tortuosity factor, characteristic pathway diameter and density of triple phase boundaries is the key to designing a fuel cell which shows high electrochemical performance. Lack of stability has been the main barrier to commercialization of SOFC technology. Parameters influencing the degradation of Ni–YSZ supported SOFCs such as Ni migration inside the anode during prolonged operation are discussed. The longest Ni-supported SOFC tests reported so far are examined and the crucial role of chromium poisoning due to interconnects, stack design and operating conditions in degradation of SOFCs is highlighted. The importance of calcination and milling of YSZ to development of porous structures suitable for Ni infiltration is explained and several methods to improve the electrochemical performance and stability of Ni–YSZ anode supported SOFCs are suggested.The authors would like to acknowledge Future Energy Systems Research Initiative (Grant Number RES0031233) and grant PID2019-107106RB-C32 funded by MCIN/AEI/10.13039/ 50110001103 for financial support of the research carried out at the University of Alberta and Instituto de Nanociencia y Materiales de Aragón (CSIC-Unizar) and during preparation of the current manuscript.Peer reviewe