Microstructural Evolutions, Hot Deformation and Work Hardening Behaviour of Novel Al–Zn Binary Alloys Processed by Squeezing and Hot Extrusion

S. Sivasankaran,K. R. Ramkumar,Hany R. Ammar,Fahad A. Al‑Mufadi,Abdulaziz S. Alaboodi,Osama Mohamed Irfan 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.4

The main goals of this work were to manufacture novel Al–Zn extruded alloys by varying the Zn content (0, 10, 20, 30 wt%),investigate the microstructural evolutions, hot deformation, and work hardening behaviour by hot compression test at differenttemperatures (25 °C, 75 °C, 150 °C, 225 °C, 300 °C). Al–20Zn alloy microstructure revealed α-Al and uniform distributionof (α + η) phases, coherent (α + η) crystals in GBs with casting defect-free surfaces, and effective interactions of pinningdislocations which led to improve mechanical performance of Al–20Zn alloy, as compared to the other alloys. The observedengineering stress–strain curve results revealed the decrease of stress with increasing of temperature due to flow softening,dynamic recovery and dynamic recrystallization. These results displayed also an increase of stress value with increasingof Zn content due to the precipitation of high density (α + η) phase in the matrix and GBs, increasing of forest and mobiledislocations density with strain fields, and the formation of fine dendrites. Work hardening rate (WHR) of extruded samplesdisplayed three stages: stage I, WHR decreased slightly with increasing of temperature up to 75 °C and decreased drasticallyfrom 75 °C to 300 °C due to softening; stage II, WHR maintained constant due to balance between dislocation generationsand dislocation annihilation; stage III, WHR slightly increased due to strain hardening of (α + η) phase. WHR was observedto increase considerably with increasing of Zn content due to the formation and dispersion of high density of (α + η) phasein the Al matrix and GBs. Deformation micro-localization in terms of different characteristics was examined and reportedon the deformed samples after hot-compression test through SEM micrographs.

Effect of TiB2/Gr Hybrid Reinforcements in Al 7075 Matrix on Sliding Wear Behavior Analyzed by Response Surface Methodology

S. Sivasankaran,K. R. Ramkumar,Fahad A. Al‑Mufadi,Osama M. Irfan 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.6

Al 7075 alloy matrix reinforced with different weight percentage of titanium borides (TiB2, 0, 1.5, 3, 4.5 and 6 wt%) and1 wt% graphite (Gr) hybrid composites were synthesized by in-situ liquid metallurgy route, then the sliding wear characteristicswere performed and investigated in this research work. TiB2reinforced as 0, 1.5, 3, 4.5 and 6 wt% by the in situchemical reaction of KBF4and K2TiF6salts and 1 wt% Gr with the Al 7075 matrix were added constantly in the melt. Severalexperiments were carried out to examine the wear behavior of the fabricated composite specimens through a tribometer atambient temperature. The weight percentage of reinforcement (TiB2 particles), the applied load, the sliding velocity (SV),and the sliding distance (SD) were selected as process parameters at five different levels. The response surface methodology(RSM) was used to conduct the experiments as RSM is the feasible and accurate method employed for optimizing to set theparameters. To check the significance of the developed model by RSM, ANOVA and confirmatory tests were also accomplished. FESEM surface morphology was also carried out to illustrate the uniform dispersion of the TiB2–Gr particulatesin Al 7075 matrix. The predicted wear characteristics from the developed model were well agreed with the experimentalresults. The obtained results were explained that both the increase in the percentage of RF and SV have dropped the wearloss (WL) curve whereas the load at all SVs and the SDs were uplifted the WL. The worn surface morphology explainedthat the adhesive mechanisms were dominated during the sliding wear test. Further, severe and mild wear occurred duringhigher load and lower load respectively.

Synthesis, Microstructures and Mechanical Behaviour of Cr0.21Fe0.20Al0.41Cu0.18 and Cr0.14Fe0.13Al0.26Cu0.11Si0.25Zn0.11 Nanocrystallite Entropy Alloys Prepared by Mechanical Alloying and Hot-Pressing

Yaser A. Alshataif,S. Sivasankaran,Fahad A. Al‑Mufadi,Abdulaziz S. Alaboodi,H. R. Ammar 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.1

Four component Cr0.21Fe0.20Al0.41Cu0.18medium entropy alloy (Quaternary, 4C-MEA) and six componentCr0.14Fe0.13Al0.26Cu0.11Si0.25Zn0.11high entropy alloy (sexinary, 6C-HEA) were designed and developed in non-equiatomicratio to attain improved mechanical properties. These 4C-MEA, and 6C-HEA were synthesized via mechanical alloying(MA), and consolidated by hot pressing (HPing) at 723 K. For comparison, the same atomic ratio of four and six componentsof coarse grain alloys (4C-CGA and 6C-CGA) were also manufactured by conventional blending method. Nanocrystallitesize powders of 27 ± 5.20 nm and 38 ± 3.7 nm were achieved for 4C-MEA and 6C-HEA respectively after 20 h MA. Thephase evolutions, structural properties, and powder surface morphologies were characterized using X-ray diffraction andseveral electron microscopes. The 4C-MEA has possessed more quantity of body centred cubic (BCC) and less amountof face centred cubic (FCC) phases due to the more solid dissolution of 4 components. However, 6C-HEA exhibited morequantity of FCC and a small amount of BCC phases due to the incorporation of more FCC components compared to 4C-MEAand less solid dissolution due to more atomic radius difference among the mixing elements (atomic radius of Cr = 166 pm,Fe = 156 pm, Al = 118 pm, Cu = 145 pm, Si = 111 pm and Zn = 142 pm). The HPed samples produced ultra-fine crystallitesize of 177 nm and 499 nm for 4C-MEA and 6C-HEA respectively. Further, 4C-MEA and 6C-HEA exhibited the ultimatecompressive strength (UCS) of 365 MPa and 456 MPa respectively due to dissolution and lattice distortion of mixing elements. Also, 6C-HEA possessed Vickers hardness strength of around 1.97 GPa which was 2 times higher than 4C-MEA. The theoretical background of various strengthening mechanisms, various physicochemical, thermodynamic parameters, andfour core effects behind the improved properties in entropy alloys was discussed and reported. The dislocation strengtheningand solid solution strengthening were the major factors in exhibiting more UCS in 4C-MEA and 6C-HEA than 4C-CGAand 6C-CGA.

Manufacturing Methods, Microstructural and Mechanical Properties Evolutions of High‑Entropy Alloys: A Review

Yaser A. Alshataif,S. Sivasankaran,Fahad A. Al‑Mufadi,Abdulaziz S. Alaboodi,Hany R. Ammar 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.8

High entropy alloys (HEAs) are being attracted recently by several researchers, scientists, and academicians to achieveextraordinary and outstanding properties that cannot be obtained from conventional alloys. HEAs are multicomponent alloysin which a minimum of five metallic elements are mixed in an equal molar or non-equal molar ratio. The rapid growth ofthis field produces a huge amount of scientific papers over the last decade. However, still, there is a need to review variousmanufacturing methods and their results. Also, the outcome of the scientific articles related to HEAs has ignored the variousmethods of synthesizing and manufacturing. In this review article, an attempt was made and largely concentrated on themethods and techniques that can be used in the manufacturing and synthesizing of the HEAs. Recently, the properties ofHEAs become much better when compared to conventional alloys. Some techniques have succeeded in producing ultrafinemicrostructure grains which become a leap in industrial fields. Now, the manufacturing methods of conventional alloys arealmost familiar and implemented according to the suggestions given by the researchers and academicians based on their work. Therefore, the present review article has demonstrated various methods of manufacturing of HEAs with novel schematicswith a preview description for more understanding of the basic work criteria. Besides, this article has reviewed the outcomesof several research articles related to several methods, then compared the outcome of each method with the correspondingmechanical properties, and major challenges of HEAs are discussed and reported.

Synthesis and Measurement of Optical Light Characterization for Modern Cost-fewer Polyvinyl Chloride Nanocomposites Thin Films

Ahmed Thabet,Fahad A.Al Mufadi,A. A. Ebnalwaled 한국전기전자재료학회 2024 Transactions on Electrical and Electronic Material Vol.25 No.1

Modification of polyvinyl chloride (PVC) has drawn more attention in modern electronic industries that gives the modified substance particular qualities. The present study aims to explore the impact of pristine and surfactant-modifi ed clays (montmorillonite and bentonite) on the optical properties of a polyvinyl chloride polymer film. In this paper, it has been fabricated various concentrations of clay nanoparticles with the polymeric substance polyvinyl chloride. Tetrahydrofuran was used as the solvent in SOL–GEL fabrication process and the samples were formed into thin fi lms. Then, clay nanoparticles are experiment for their impact on the optical light characterization of polyvinyl chloride (PVC) at various wavelengths. A comparative study has been studied the effective type and concentrations of clay nanoparticles on light transmission and absorption performance with respect to pure base matrix polymer. Finally, this study has been got the optimal concentrations of clay nanoparticles that were required for regulating the optical light characterization of polyvinyl chloride.