Showing papers in "Acta Materialia in 2018"

TL;DR: In this paper, the authors present a review of recent developments in the field of deformation behavior of high manganese face-centered cubic γ-Fe alloys, referred to as twinning-induced plasticity, or TWIP, steels.

TL;DR: In this paper, a combination of high-speed imaging and schlieren imaging, as well as multiphysics modeling, was employed to elucidate the effects of the interaction between the laser beam and the powder bed.

TL;DR: In this article, the mechanisms for the formation of basal texture variations were systematically investigated based on the twinning and dynamic recrystallization (DRX) during extrusion using electron back-scatter diffraction (EBSD) characterization.

TL;DR: In this paper, the authors review the science and technology of various types of non-RE materials for permanent magnet applications and discuss the current status, challenges, potentials, and future directions for these candidates.

TL;DR: In this article, the diffusion coefficients of Co, Cr, Fe and Mn tracers were determined in polycrystalline CoCrFeNi and CoCr FeMnNi HEAs using the radiotracer method in the temperature interval of 1073-1373 K.

TL;DR: In this paper, a NbTaTiV refractory HEA with a single body-centered-cubic (BCC) structure using an integrated experimental and theoretical approach was developed.

TL;DR: In this paper, gas-atomized powders of two ternary alloys, Al-3.60Mg-1.18Zr and Al 3.57Zr, were densified via laser powder bed fusion.

TL;DR: In this article, a non-weldable Ni-based superalloy was fabricated by powder bed-based selective electron beam melting (S-EBM) and cracks were consistently found to propagate intergranular and the effect of crystallographic misorientation on the cracking behavior was investigated.

TL;DR: In this article, a low-alloyed Mg-2Sn-2Ca alloy (in wt.%) is reported, which exhibits tunable ultra-high tensile yield strength (360-440 MPa) depending on extrusion parameters.

TL;DR: In this paper, the challenges of instrumented micro-and nanomechanical testing at elevated temperature are summarized and a special focus is laid on the pitfalls of micro-compression testing with its stringent boundary conditions often hampering reliable experiments.

TL;DR: In this paper, the dynamics of powder spattering in the laser powder bed fusion (LPBF) additive manufacturing (AM) process were investigated with in-situ high-speed high-energy x-ray imaging.

TL;DR: In this paper, the microstructure and mechanical properties of commercially pure titanium (CP-Ti) gyroid scaffolds with different unit cell sizes and sample orientations were evaluated and the average microhardness of the struts was 2.27 GPa, which is ∼50% higher than that of dense cast CP-Ti.

TL;DR: In this article, the phase evolution of two HEAs, CoCrCuFeNi and AlCoCrFeNi, were designed as matrix alloys, where Ni and Mo are alloyed.

TL;DR: In this article, the formation of different crystal structures (FCC, BCC, or FCC+BCC mixture) and its effects on the resulting mechanical properties of this series of HEAs, both in tension and compression, were evaluated.

TL;DR: In this article, the effects of laser power and scanning speed alteration on the microstructure, transformation temperatures, texture, and shape memory response of Ni50.8Ti49.2 were investigated.

TL;DR: An objective (data-driven) approach to efficiently and accurately link a three-dimensional (3-D) microstructure to its effective (homogenized) properties is developed, and it is demonstrated that this CNN based approach not only learns interpretable microst structure features, but also leads to improved accuracy in property predictions for new microstructures, while achieving a dramatic reduction in the computation time.

TL;DR: In this paper, a single-phase CrCoNi medium-entropy alloys (MEA) with various heterogeneous microstructures, using cold rolling followed by annealing at various temperatures, was characterized using hat-shaped specimens in Hopkinson-bar experiments.

TL;DR: The tensile properties, mode I fracture toughness, fatigue crack growth behavior, and unnotched fatigue strength of additively manufactured Ti-6Al-4V (Ti64) alloy using selective laser melting (SLM) technique were investigated in this article.

TL;DR: Li et al. as mentioned in this paper analyzed the deformation and fracture behavior of layered Ti-Al metal composite by in-situ observations during the tensile deformation, and provided a new structural strategy to simultaneously improve strength and ductility.

TL;DR: In this article, a new grain boundary engineering approach based on compositionally conditioning the grain boundaries instead of the bulk material was proposed to enhance grain boundary cohesion and retard capillary driven grain coarsening.

TL;DR: In this article, the authors argue that the large interfacial strain needed to achieve bonding does not necessarily require adiabatic shear instability to trigger, and instead, they suggest that the interaction of strong pressure waves with the free surface at the particle edges can cause hydrodynamic plasticity that effects bonding, without requiring Shear instability, and they proceed on this basis to postulate and confirm a proportionality between critical velocity and the bulk speed of sound.

TL;DR: In this paper, the coarsening of L12 precipitates in a face-centered-cubic (fcc) (NiCoFeCr)94Ti2Al4 high-entropy alloy (HEA) at temperatures between 750 and 825

TL;DR: The structural and compositional evolution of precipitates in Al-Mg-Si-Cu alloys were systematically investigated by atomic resolution high-angle annular dark-field scanning transmission electron microscopy and atom probe tomography as mentioned in this paper.

TL;DR: In this paper, an off-equiatomic Cr26Mn20Fe20Co20Ni 14 high-entropy alloy was solutionized and isothermally aged at temperatures between 600°C and 1000°C for times to 1000

TL;DR: In this article, an equiatomic, single-phase TiZrNbHfTa high-entropy alloy was subjected to high-pressure torsion, leading to a grain size below 100nm.

TL;DR: In this paper, the deformation mechanisms were systematically investigated using EBSD and TEM for samples strained to 1.3, 5% and 16% and a substantial 33.3% uniform elongation was achieved.

TL;DR: It is demonstrated that a subsequent homogenization heat treatment can effectively homogenize the AM alloy and remove the deleterious δ phase, and the combined experimental and modeling methodology can be extended to elucidate the phase evolution during heat treatments in a broad range of AM materials.

TL;DR: In this article, the deformation responses at 77 and 293 K of a FeCoNiCr high-entropy alloy, produced by a powder metallurgy route, were investigated using in situ neutron diffraction and correlative transmission electron microscopy.

TL;DR: In this paper, a metastable β-type Ti-25Nb-0.7Ta-2Zr (at.%) alloy was investigated with two starting states: one is ω-free and the other one contains a high number density of nanometer-sized (∼1.23nm) ω particles.

TL;DR: In this article, the authors investigated the sequence of precipitation on grain boundaries in comparison to the bulk in a model Al-Zn-Mg-Cu alloy and quantified the difference in kinetics between grain boundary and bulk precipitation.