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Iron and chromium powders were mixed and mechanically alloyed via high-energy ball milling for different time durations (2–20 h) to produce an alloy powder with a nominal composition of Fe-9Cr (wt.%). The milled Fe-9Cr powders were analyzed using scanning electron microscopy (SEM), x-ray diffraction (XRD) and transmission electron microscopy (TEM) to understand the impact of ball milling (BM) time...
We report the behavior of Mg vapor and CO by dynamic simulation and an experimental study under vacuum. The results of the density functional theory indicated that the interaction of a single CO molecule with the Mg(100) surface was only physical adsorption. During the interaction of two CO molecules with the Mg(100) surface, a strong C-C bond was formed between C1 and C2, and C1-O1 and C2-O2 were...
The mechanical response of Ni-based single-crystal superalloys is known to be sensitive to the microstructural state, i.e., the shape and size of the γ′ precipitates when exposed to high-temperature conditions. The magnitude and sign of the natural lattice misfit between the γ and γ′ phases play the most crucial role in establishing a controlled size, shape, and distribution of γ′ precipitates during...
The complicated metal-based additive manufacturing (AM) process involves various sources of uncertainty, leading to variability in AM products. For comprehensive uncertainty quantification (UQ) of AM processes, we present a physics-informed data-driven modeling framework, in which multilevel data-driven surrogate models are constructed based on extensive computational data obtained by multiscale multiphysics...
Due to the uncertainty in calibrating the crystal plasticity (CP) model parameters, the present study quantifies the associated variability in the resulting mechanical response via a two-step process. First, a genetic algorithm framework is used to obtain the statistical distributions for the appropriate CP parameters. Second, those distributions are used in a first-order, second-moment method to...
The cold spray materials deposition process has been investigated for manufacturing oxide dispersion-strengthened (ODS) steel fuel cladding tubes. Gas-atomized 14YWT ODS steel powder was used as the feedstock material. A parametric investigation of the cold spray process involving substrate materials of various hardnesses, gas preheat temperatures, and carrier gas compositions was performed to achieve...
The aim of the present study is to investigate the feasibility of using liquid ethanol as a precursor for carburization of MoO3. Ethanol vapor was transported by Ar flow to a MoO3 powder bed during heating to 1000 K and 1100 K and during holding at these temperatures for different times. Single-phase Mo2C was obtained at 1000 K, 1050 K, and 1100 K within isothermal reaction time of 60 min, 30 min,...
This paper develops a bottom-up and top-down multi-scale modeling framework for predicting fatigue crack nucleation in structures of titanium alloys, e.g., Ti-7Al. A parametrically homogenized constitutive model (PHCM) and a parametrically homogenized crack nucleation model (PHCNM) are developed from computational homogenization of crystal plasticity finite element simulation results performed on...
The interactions of moving dislocations with various point, line and planar defects during hot working of polycrystalline face-centred cubic alloys are studied. Experimental parameters from three austenitic steels and a Ni-base superalloy are integrated with a dislocation model within a multi-scale framework. The combination of these inputs is used to explain the microstructure evolution and flow...
This paper explores a formal strategy for the extraction of single-crystal elastic constants of cubic polycrystalline metals based on the optimal design of spherical indentation experiments. Recent work has formulated the extraction of elastic constants using a two-step protocol. The first step established a surrogate model to capture the dependence of the indentation elastic modulus on the grain...
Data-driven tools for finding structure–property (S–P) relations, such as the Materials Knowledge System (MKS) framework, can accelerate materials design, once the costly and technical calibration process has been completed. A three-model method is proposed to reduce the expense of S–P relation model calibration: (1) direct simulations are performed as per (2) a Gaussian process-based data collection...
The overarching aim of this paper is to explore the use of machine learning (ML) to predict the microstructure-sensitive evolution of a three-dimensional (3D) crack surface in a polycrystalline alloy. A convolutional neural network (CNN)-based methodology is developed to establish spatial relationships between micromechanical/microstructural features in a cyclically loaded, uncracked microstructure...
Precipitation evolution-induced hardness variation in 6082-T6 alloy during various thermal histories of welding and subsequent paint baking was characterized systematically. Precipitation evolution in various subzones of the heat-affected zone (HAZ) from the weld toe to the base materials was precisely identified by transmission electron microscopy. Under heating processes of welding and baking with...
Cu/SiCP composites with high strength and high conductivity were prepared by in situ carbonization reaction of silicon. The Cu-Si powder and C powder were mechanically mixed, and in situ carbonized at 850°C for 48 h, then oxidation-treated in dry air atmosphere at 650°C for 8 h, followed by reduction-treating in hydrogen atmosphere at 500°C for 90 min. The results showed that some nano-scale and micron-scale...
In the metal extraction process, recovery of valuable elements from fly ash can have economic benefits and maximize its utilization. Extraction of Mg and Ca from fly ash by the carbochlorination method was studied as a function of carbochlorination temperature, time, carbon content, pellet diameter, and chlorine gas flow rate. The kinetic regime of the carbochlorination of Mg- and Ca-bearing compounds...
We report on the establishment of a framework to determine the value of the pressure-related atomic diffusion coefficient, D, and its use. Moreover, we clarify the underlying relationships between the as-determined D and the active densification mechanisms during crystalline powder sintering. During spark plasma sintering, the theoretical framework is validated by comparing the densification behaviors...
The effects of two-stage thermomechanical processing on the microstructure and properties of Cu-15Ni-8Sn-1.0Zn-0.5Al-0.2Si alloy have been investigated by optical microscopy, scanning electron microscopy, transmission electron microscopy, and mechanical and electrical property testing. Spinodal decomposition and β-Ni3Sn precipitates with L12 ordering structure appeared in the preaged alloy. The crystal...
The ferrosilicon nitride used for steelmaking has been synthesized by direct nitriding. The relationship between the reaction temperature and nitriding effect was investigated. The results show that the initial reaction temperature between FeSi75 and nitrogen is approximately 900°C. Increasing holding temperature or prolonging holding time is beneficial to increase the nitrogen content in the nitrided...
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