Intelligent Design of High Strength and High Conductivity Copper Alloys Using Machine Learning Assisted by Genetic Algor

Metallic alloys for a given application are usually designed to achieve the desired properties by devising experimentsbased on experience, thermodynamic and kinetic principles, and various modeling and simulation exercises.However, the influence of process parameters and material properties is often non-linear and non-colligative. Inrecent years, machine learning (ML) has emerged as a promising tool to dealwith the complex interrelation betweencomposition, properties, and process parameters to facilitate accelerated discovery and development of new alloysand functionalities. In this study, we adopt an ML-based approach, coupled with genetic algorithm (GA) principles,to design novel copper alloys for achieving seemingly contradictory targets of high strength and high electricalconductivity. Initially, we establish a correlation between the alloy composition (binary to multi-component) andthe target properties, namely, electrical conductivity and mechanical strength. Catboost, an ML model coupledwith GA, was used for this task. The accuracy of the model was above 93.5%. Next, for obtaining the optimizedcompositions the outputs fromthe initial model were refined by combining the concepts of data augmentation andPareto front. Finally, the ultimate objective of predicting the target composition that would deliver the desired rangeof properties was achieved by developing an advancedMLmodel through data segregation and data augmentation.To examine the reliability of this model, results were rigorously compared and verified using several independentdata reported in the literature. This comparison substantiates that the results predicted by our model regarding thevariation of conductivity and evolution ofmicrostructure and mechanical properties with composition are in goodagreement with the reports published in the literature.

Electrolytic production of Cu-Ni alloys in CaCl_2-Cu_2S-NiS molten salt

An alternative metal/alloy production method,known as direct electrochemical reduction(DER),was introduced for the fabrication of CuNi alloys from mixed sulfides(Cu2S,NiS)under both galvanostatic and potentiostatic conditions.The influences of the process parameters(e.g.,cell voltage and current)on the compositions of the reduced compounds were investigated to yield industrially desirable alloys,namely,CuNi10,CuNi20,and CuNi30.The electrochemical behaviors of Cu2S and NiS in CaCl2 melt were examined at a temperature of 1200°C via cyclic voltammetry(CV).Based on the CV results,the cathodic reduction of Cu2S occurred in one step and cathodic reductions of NiS occurred in two steps,i.e.,Cu2S?Cu for copper reduction and NiS?Ni3S2?Ni for nickel reduction.Galvanostatic studies revealed that it was possible to fabricate high-purity CuNi10 alloys containing a maximum sulfur content of 320×10-6 via electrolysis at 10 A for 15 min.Scanning electron microscopy along with energy-dispersive X-ray spectrometry and optical emission spectroscopy(OES)examinations showed that it was possible to fabricate CuNi alloys of preferred compositions and with low levels of impurities,i.e.,less than 60×10-6 sulfur,via DER at 2.5 V for 15 min.

Inhibition effect of 2-amino-5-ethyl-1,3,4-thiadiazole on corrosion behaviour of austenitic stainless steel type 304 in dilute HCl solution

The corrosion inhibition of type 304 austenitic stainless steel by 2-amino-5-ethyl-1, 3, 4-thiadiazole(TTD) compound and the electrochemical behaviour in dilute HCl solution were investigated through potentiodynamic polarization test, mass loss techniques and potential measurements. The results show that the organic derivative is highly effective with a maximum inhibition efficiency of 70.22% from mass loss analysis, while 74.2% is obtained from polarization tests. Observation of the scanning electron micrographs shows the absence of corrosion products due to electrochemical influence of TTD on the surface morphology of the steel. X-ray diffractometry reveals the absence of phase compounds and complexes on the steel samples after exposure. TTD adsorption on the steel surface obeys the Langmuir, Frumkin and Freundlich adsorption isotherms. Corrosion thermodynamic calculations reveal the inhibition mechanism occurs through chemisorption process and results from statistical analysis depict the strong influence of inhibitor concentration on the electrochemical performance of the TTD.

Implications of twinning on the microstructure development,crystallographic texture and mechanical performance of Mg alloys-a critical review

Deformation twinning is profusely activated in the Mg alloys due to lower critical resolved shear stress(CRSS) compared to the non-basal slip systems(prismatic and pyramidal ) and plays a significant role in texture reorientation, grain refinement and enhancement of mechanical performance. Twinning is a sequential process comprising twin nucleation, twin propagation and twin growth, hence several intrinsic and extrinsic parameters that facilitate or suppress the process have been critically reviewed. The dependence of twinning on the grain size, deformation temperature, favorable grain orientation and shear strain have been thoroughly discussed in the context of published literature and an attempt has been made to provide a benchmark conclusive finding based on the majority of works. Furthermore, the subsequent effect of twinning on the mechanical performance of Mg alloys, including ductility, formability and tension-compression asymmetry has been discussed in detail. Lastly, the stability of twins, including stress and thermal stability, is summarized and critical issues related to pertinent bottlenecks have been addressed.

Casting properties of ASTM A128 Gr.E1 steel modified with Mn-alloying and titanium ladle treatment

This work aims to produce a high manganese steel with more refined austenite grains and better wear resistance without sacrificing the toughness and tensile properties by Mn alloying and Ti ladle treatment in comparision to ASTM A128 Gr.E1 steel (1.0C-13Mn) that is mostly used in the mining industry.The 1.0C-17Mn-xTi alloys (x=0,0.05 and 0.1,in wt.%) were prepared.A relationship was established between the microstructures and mechanical properties of the as-cast and solution annealed alloys.Increasing Ti content increases the stable Ti(CN) phase on and beside the grain boundaries and decreases up to 37% the austenite grain size of the as-cast alloy with 0.10wt.% Ti.Correspondingly,after solution annealed,optimized titanium content (0.05wt.%) results in significant improvements in wear resistance,hardness,elongation,yield and tensile strengths by 44%,31%,30%,8% and 12%,respectively,except 9% decrease in impact toughness compared to ASTM A 128 Gr.E1 steel without modification.These results show that 1.0C-17Mn-0.05Ti alloy can be used for parts exposed to high load wear and applied in conditions where relatively high tensile properties with sufficent ductility is needed.

Effect of Mixing Strategy on the Structure-Properties of the PLA/PBAT Blends Incorporated with CNC

Polylactide(PLA)/poly(butylene adipate-co-terephthalate)(PBAT)blend nanocomposites including 3 wt%of cel-lulose nanocrystals(CNCs)were prepared by melt compounding method in a twin-screw extruder and an inter-nal mixer.Blend nanocomposites were formulated by diluting three different masterbatches prepared by solution casting method that contained 7 wt%of CNC.These masterbatches were:(m1)PLA/PBAT/CNC masterbatch;(m2)PLA/CNC masterbatch;and(m3)PBAT/CNC masterbatch.These were to explore how different prepara-tion methods affect the dispersion and localization of CNC and hence the properties of PLA/PBAT/CNC blend nanocomposites.Scanning electron microscopy(SEM)was used to study the structural changes of the blends.Rheological properties of PLA/PBAT blends and PLA/PBAT/CNC blend nanocomposites were also investigated.In the samples prepared by internal mixer,the rheological behavior of blend nanocomposite prepared through premixing of CNC particles with PLA showed a transition from liquid-like to a gel-like behavior.According to the rheological results and differential scanning calorimetry(DSC)analysis,it was found that the CNC overall enhanced the viscoelastic properties of blends and improved the PLA crystallization,respectively.Dynamic mechanical analysis(DMA)illustrated that the incorporation of CNC also enhanced the elastic modulus of PLA/PBAT blends specifically above the glass transition temperature of PLA.The expected improvements in mechanical properties did not occur due to the possible existence of residual solvent in the blends.

Recent progress and perspective in additive manufacturing of EMI shielding functional polymer nanocomposites

Because of rapid progress in the electronics industry,the market has faced a huge demand for novel materials in the field of electromagnetic interference(EMI)shielding.Conductive functional polymer composites have demonstrated great potential to fulfill this requirement.To synthesize the polymeric composites,functional conductive nanoadditives such as graphene,carbon nanotubes,and MXene are commonly added to polymeric matrices,and the conductive polymer nanocomposites exhibit promising electrical conductivity as well as EMI shielding performance.Additive manufacturing(AM),also referred to as threedimensional(3D)printing,has been increasingly employed to fabricate complicated geometry components in the medical,aerospace,and automotive industries.AM has also been used to fabricate advanced EMI shielding materials for sensors,supercapacitors,energy storage devices,and flexible electronics.This review aims at introducing the different 3D printing methods applied for the fabrication of EMI shielding polymer nanocomposites.The impact of the AM process on the functionality of the samples is also reviewed.Additionally,the influence of the nanofiller type and amount on the microstructure and performance of the fabricated nanocomposites is discussed.Finally,the prospects and recommended works for future study are outlined.

Investigation of the phase space in lead‐free(K_(x)Na_(1-x))_(1-y)Li_(y)(Nb_(1-z)Ta_(z))O_(3) ferroelectric ceramics

A library of ceramic compounds based on the lead-free(K_(x)Na_(1-x))1-yLiy(Nb1-zTaz)O_(3)solid solution has been synthesized and characterized using high-throughput experimentation(HTE)method.The phase space previously reported by Saito and Takao has been expanded to{{x,0.1,1.0},{y,0,0.1},{z,0,0.2}},and new phase boundaries are observed.The relative density values show that with the appropriate sintering temperature,~92%of the theoretical density can be reached.The relative permittivity values show that with increasing amount of K+and Ta5+,the dielectric constant values increase.The effect of density on the dielectric constant values is however minimal.Resistivity values ranging from 109 to 1013Ω·cm are obtained for the samples.The piezoelectric charge coefficient values for selected compositions show that higher values are obtained close to the phase boundaries rather than away from them.The properties for the ceramic library using the HTE method are generally 15%-20%less than from the conventional method.This method is therefore more suited for screening of sample compositions than for producing samples with high piezoelectric properties.

Distilling physical origins of hardness in multi-principal element alloys directly from ensemble neural network models

Despite a plethora of data being generated on the mechanical behavior of multi-principal element alloys,a systematic assessment remains inaccessible via Edisonian approaches.We approach this challenge by considering the specific case of alloy hardness,and present a machine-learning framework that captures the essential physical features contributing to hardness and allows high-throughput exploration of multi-dimensional compositional space.The model,tested on diverse datasets,was used to explore and successfully predict hardness in Al_(x)Ti_(y)(CrFeNi)_(1-x-y),Hf_(x)Co_(y)(CrFeNi)_(1-x-y)and Al_(x)(TiZrHf)_(1-x)systems supported by data from density-functional theory predicted phase stability and ordering behavior.The experimental validation of hardness was done on TiZrHfAlx.The selected systems pose diverse challenges due to the presence of ordering and clustering pairs,as well as vacancy-stabilized novel structures.We also present a detailed model analysis that integrates local partial-dependencies with a compositional-stimulus and model-response study to derive material-specific insights from the decision-making process.