Showing papers in "Acta Materialia in 2019"

TL;DR: In this article, a materials design strategy combining a machine learning (ML) surrogate model with experimental design algorithms to search for high entropy alloys (HEAs) with large hardness in a model Al-Co-Cr-Cu-Fe-Ni system was proposed.

TL;DR: In this paper, a new ab initio entropy descriptor was developed to assist in selection of candidate compositions for synthesis of high entropy and entropy stabilized carbides. But the proposed descriptor is not suitable for high-energy ball milling and spark plasma sintering.

TL;DR: In this article, the role of alloy constitution is explored in three classical alloy design regimes: an alloy containing no grain refiners (Ti 6Al 4V); an alloy only containing grain refining solutes (Ti 3Al 8V 6Cr 4Mo 4Zr); and an alloy including both grain refining and nucleant particles (Ti3Al 8v 6Cr4Mo 4zr+La2O3).

TL;DR: In this article, a precipitation-strengthened FeCoNiCrTi0.2 high-entropy alloy strengthened by two types of coherent nano-precipitates but with the same composition was fabricated, and its tensile properties at room and cryogenic temperatures (77 K) and the corresponding defect-structure evolution were investigated.

TL;DR: In this paper, the authors present a heterogeneous-structures-architecting strategy, in which they design bulk high-entropy alloys with the largelyenhanced strength-ductility trade-off, possessing a yield strength of 711 MPa, a tensile strength of 928 MPa and a uniform elongation of 30.3%.

TL;DR: In this article, a high strength in-process and post-process friendly Al alloy was developed for the selective laser melting (SLM) process, one of the most commonly used additive manufacturing techniques.

TL;DR: This work provides an alternative route of computational design of HEAs, which is also applicable to accelerate the discovery of other metal alloys for modern engineering applications.

TL;DR: In this article, a hierarchical microstructure design was employed to improve the mechanical properties of an interstitial carbon doped high-entropy alloy by cold rolling and subsequent tempering and annealing.

TL;DR: A review of recent experimental evidence and simulation results enumerating the development of the hydrogen-enhanced localized plasticity (HELP) mechanism as a viable hydrogen embrittlement mechanism for structural materials is presented in this article.

TL;DR: In this paper, the influence of Laves phases on the room temperature tensile properties of laser additive manufactured Inconel 718 has been investigated, and a yield strength model has been developed to reveal this influence in terms of numbers.

TL;DR: In this paper, the formation possibility of a new (Zr0.25Nb 0.25Ti 0.5V0.040R) high-entropy ceramics (ZHC-1) was first analyzed by the first-principles calculations and thermodynamical analysis and then it was successfully fabricated by hot pressing sintering technique.

TL;DR: In this paper, the authors investigated the effects of powder oxidation on the molten pool dynamics and defect formation during laser additive manufacturing (LAM) of virgin, stored, and reused powders.

TL;DR: In this article, cold-rolling and annealing an equiatomic CrCoNi alloy was used to produce heterogeneous, partially recrystallized microstructures. And the results showed that this approach dramatically increased the yield strength (to ∼1100 MPa) while retaining good ductility (total elongation ∼23%).

TL;DR: In this paper, an additively manufactured Ti-6Al-4V alloy was used to obtain the bimodal microstructure consisting of globular α by heat treatment alone.

TL;DR: In this paper, the influence of interstitial content, microstructure and compositional homogeneity states on the mechanical behavior of equiatomic CoCrFeMnNi HEAs at room temperature was discussed.

TL;DR: In this paper, the authors showed that duplex annealing at temperatures below the β transus temperature of the alloy would lead to such a microstructure while retaining the mesostructure, whose nature depends on the process parameter combinations utilized.

TL;DR: In this article, the properties of 15 single-phase and 11 multi-phase refractory complex concentrated alloys (RCCAs) were investigated using the CALPHAD approach and phase diagrams were calculated to identify the solidus (melting, Tm) temperatures and volume fractions of secondary phases.

TL;DR: In this paper, the authors examined the deformation behavior of a Mg88Zn4Y7 extruded alloy, which contains ∼86vol% LPSO phase, on the temperature, loading orientation, and extrusion ratio.

TL;DR: In this paper, an Al-Zn-Mg-Cu alloy (AA7075) was processed by high pressure torsion (HPT) at room temperature and 200°C, with an objective to reveal the deformation-induced precipitation and segregation of elements at grain boundaries.

TL;DR: In this paper, a combined experimental and computational modeling study on the scraping type of powder-spreading process, in order to understand the fundamental mechanisms of the packing of the powder layer, is presented.

TL;DR: In this article, the detailed microstructure evolution occurring in the HAZ bands has been revisited, based on new evidence, and is shown to involve both dark and white etching bands.

TL;DR: In this paper, the effect of elemental combinations on the friction stress and Hall-Petch relationship in medium entropy alloys (MEAs) and high entropy alloy (HEAs) was reported.

TL;DR: In this article, microstructures and mechanical properties are evaluated in austenitic stainless steel structures fabricated by directed energy deposition (DED) considering the effects of applied loading orientation, build geometry, and distance from the deposition baseplate.

TL;DR: In this paper, a design strategy based on overall valence electron concentration (OVEC) is developed, and a coherent D022 superlattice (noted as γ″ phase) with superior strengthening effect is designed.

TL;DR: In this article, the authors studied the compression-compression fatigue behavior and the underlying fatigue mechanism of Gyroid cellular structures (GCS), a typical TPMS porous structure, and found that the fatigue ratio of GCS reaches 0.35 for as-built samples and can be raised to 0.45 after sandblasting treatment.

TL;DR: In this article, a high density of vacancies and their clustering have been detected by newly developed low temperature hydrogen thermal desorption spectroscopy and positron lifetime measurements, and the promotion of crack nucleation and growth is ascribed to the evolution of damage associated with intense strain localization.

TL;DR: In this paper, three families of shell-lattices are derived from Simple-Cubic (SC), Face-Centered Cubic (FCC) and Body-centered centered cubic (BCC) tube-structures using a parameterized surface-smoothening functional.

TL;DR: In this article, a near-atomic-scale approach was used to investigate the details of the compositional decoration of grain boundaries in the coarse-grained, columnar microstructure in parts built from a non-weldable nickel-based superalloy by selective electron-beam melting.

TL;DR: In this article, the microstructures and local mechanical properties at the melt pool boundary are analyzed in details by measuring the Si phase fraction and the Si precipitate spacing by image analysis and SEM-EDS analysis.

TL;DR: In this paper, the microstructure evolution in selective laser melted (SLM) Ti-6Al-4V was studied in the as-built condition and after sub-transus heat treatments between 400°C and 800°C focusing on elemental partitioning and the role of lattice defects on precipitation of the β phase.