High Temperature Grain Research Articles

Analysis of in-bin low-temperature and high-temperature grain drying in Alberta: Specific energy, carbon costs and policy implications

Optimizing grain drying process is pivotal for both economic viability and environmental sustainability. In cold countries, supplemental heating is paramount but instigates the issue of carbon release at the same time. To curve the emission, a carbon levy has been imposed that varies with fuel types. However, there is limited knowledge of the impact of field-adaptable technologies utilizing commercialized fuels on the optimal execution of grain drying. To explore this, a comprehensive three-year on-farm grain drying study was conducted in the province of Alberta, Canada. This comparative analysis centered on three critical aspects, i.e., specific energy consumption, greenhouse gas emissions (GHGs), and operating costs. Furthermore, the research extended its projections into the year 2030, accounting for the impact of gradual carbon levies on natural gas, propane, and diesel fuel systems. Resultsshowed that indirect heaters in in-bin systems were 38 % more energy-efficient than direct heaters due to better airflow and higher initial grain temperatures, while indirect heaters with diesel burners exhibited 27.8 % lower burner turndown ratios and 35.4 % higher energy consumption than natural gas counterparts. In high-temperature drying, natural gas consumption decreased as supply air temperatures rose, with double-flow dryer showing the lowest energy consumption (6.3±1.9 GJ/t) in comparison to mixed-flow and cross-flow dryer due to waste heat recovery. Heaters and Dryers operated at varying load capacities, indicated 126–135 % increase in natural gas cost with carbon levy by 2030. Achieving lower specific energy consumption in grain drying requires precise burner and process control, along with maintenance, offering valuable guidance for producers.

The Frictional‐Viscous Transition in Experimentally Deformed Granitoid Fault Gouge

AbstractIn crustal faults dominated by granitoid gouges, the frictional‐viscous transition marks a significant change in strength constraining the lower depth limit of the seismogenic zone. Dissolution‐precipitation creep (DPC) may play an important role in initiating this transition, especially within polymineralic materials. Yet, it remains unclear to what extent DPC contributes to the weakening of granitoid gouge materials at the transition. Here we conducted sliding experiments on wet granitoid gouges to large displacement (15 mm), at an effective normal stress and pore fluid pressure of 100 MPa, at temperatures of 20–650°C, and at sliding velocities of 0.1–100 μm/s, which are relevant for earthquake nucleation. Gouge shear strengths were generally ∼75 MPa even at temperatures up to 650°C and at velocities >1 μm/s. At velocities ≤1 μm/s, strengths decreased at temperatures ≥450°C, reaching a minimum of 37 MPa at the highest temperature and lowest velocity condition. Microstructural observations showed that, as the gouges weakened, the strain localized into thin, dense, and ultrafine‐grained (≤1 μm) principal slip zones, where nanopores were located along grain contacts and contained minute biotite‐quartz‐feldspar precipitates. The stress sensitivity exponent n decreased from a large number at 20°C to ∼2.2 at 650°C at the lowest velocities. These findings suggest that high temperature, slow velocity and small grain sizes promote DPC‐accommodated granular flow over cataclastic frictional granular flow, leading to the observed weakening and strain localization. Field observations together with extrapolation suggest that DPC‐induced weakening occurs at depths of 7–20 km depending on geothermal gradient.

The influence of crack and interface oxidation on dwell fatigue crack propagation behavior of the nickel-base superalloy ATI A718Plus

The crack propagation properties are an important and often limiting factor for the commercial application of superalloys in aerospace applications where the oxidation ahead of the crack tip plays an important role. Previous research on the Ni-base superalloy A718Plus revealed that the orientation and the volume fraction of the high temperature grain boundary phases δ and η have a major influence on the dwell fatigue crack propagation rate at 650 °C in ambient air but not in vacuum. In this work, the effect of internal oxidation at the η/δ–matrix interface and its effect on dwell fatigue crack propagation and mechanical properties are examined by advanced microscopic methods and micro-cantilever testing. During crack propagation, the crack tip is exposed to air where a Nb-rich oxide layer forms and embrittles the η/δ–matrix interface causing the cracks to deflect and propagate along the oxidized interfaces. Micro-cantilever tests on the oxidized interface show that these oxide layers also significantly reduce the local strength and fracture toughness of the material. This proves that interfacial oxide layers are the underlying reason for the reduction of the dwell fatigue crack growth resistance at 650 °C, particularly in microstructures whose η/δ–matrix interfaces are oriented parallel to the crack growth direction.Graphical

Strategy of increasing protein production based on lupin and nano disintegrator technology

The article considers the problem of providing food to the population. To solve this problem, it is proposed to master the process of protein production from lupin. The cultivation of lupin will allow the development of the northern territories of the country and will make it possible to accelerate the development of the northern sea route. It has been established that of all leguminous crops, lupin has the most nitrogen-fixing ability, which will allow further use of arable land for sowing other crops and reduce the amount of nitrogen fertilizers used. It is noted that lupine feed is difficult to digest. To solve this problem, high-temperature grain processing has been developed. This technology improves the process of feeding poultry and animals, but has disadvantages such as: high-temperature processing of lupin grain contributes to the destruction of a number of amino acids and reduces the effect of the vitamin complex; significant additional costs are required for hydrothermal exposure. To eliminate these shortcomings, a new lupin processing process is proposed using a disentangulatory technology. To improve the disintegrator technology, a nanodesintegrator process is proposed by using microturbines instead of electric motors, which increases the effect of grinding the structure and activating biological systems by 19.2 times.

A Polymer-Based Metallurgical Route to Produce Aluminum Metal-Matrix Composite with High Strength and Ductility.

In this investigation, an attempt was made to develop a new high-strength and high-ductility aluminum metal-matrix composite. It was achieved by incorporating ceramic reinforcement into the metal which was formed in situ from a polymer by pyrolysis. A crosslinked PMHS polymer was introduced into commercially pure aluminum via friction stir processing (FSP). The distributed micro- and nano-sized polymer was then converted into ceramic particles by heating at 500 °C for 10 h and processed again via FSP. The produced composite showed a 2.5-fold increase in yield strength (to 119 MPa from 48 MPa) and 3.5-fold increase in tensile strength (to 286 MPa from 82 MPa) with respect to the base metal. The ductility was marginally reduced from 40% to 30%. The increase in strength is attributed to the grain refinement and the larger ceramic particles. High-temperature grain stability was obtained, with minimal loss to mechanical properties, up to 500 °C due to the Zenner pinning effect of the nano-sized ceramic particles at the grain boundaries. Fractures took place throughout the matrix up to 300 °C. Above 300 °C, the interfacial bonding between the particle and matrix became weak, and fractures took place at the particle-matrix interface.

Microstructure evolution and EBSD analysis of multi-principal element alloy coatings after high-temperature oxidation

Multi-principal element alloy coatings (MPEACs) have great application potential for high-temperature diffusion barrier coatings. The sluggish diffusion and lattice distortion of this new coating material due to its own atomic size effect give the coating excellent resistance to high temperature oxidation and grain coarsening. In this study, the high-temperature oxidation properties, and microstructure evolution of quaternary, quinary, senary, and denary alloy coatings (whose lattice distortion magnitude is linearly increased) at 1100 °C were studied. The evolution of grain orientation, size, and grain boundaries of alloy coatings after high temperature exposure were analyzed by EBSD. The results showed that from quaternary to denary alloy coatings, with the rise in lattice distortion magnitude of the alloy system, the sluggish diffusion ability of the coating at high temperatures was more obvious. Specifically, the oxidative activation energy of quaternary to denary alloy coatings is 355.41, 480.96, 478.76, and 654.03 kJ/mol, respectively. A high distortion magnitude is beneficial to increase the activation energy of the alloy coating, as a result, grain growth of alloy coatings with high activation energy is significantly inhibited, and under the combined action of storage strain energy and solute dragging, the grain boundary migration rate of the coatings also declines. Finally, the denary alloy coating shows good resistance to high temperature softening. This study provides a positive reference for promoting the application of multi-principal alloys in diffusion barrier coatings.

Core-rim microstructure formation and mechanical properties of TiB2 ceramics with TiC, B4C, Co, and Mo sintering aids

This research investigates titanium diboride (TiB2) ceramics, renowned for their exceptional properties: high hardness, chemical inertness, and thermal stability. The challenge lies in achieving dense structures through pressureless sintering, given TiB2 ceramics' high melting point and low self-diffusion coefficient. To address this, a combined method of liquid phase and reactive sintering is employed, focusing on the influence of metallic cobalt (Co) and molybdenum (Mo) as sintering aids to enhance microstructural and mechanical properties. Vacuum sintering at 1900 °C facilitates the reaction between TiC and B4C, forming TiB2, with Co improving wettability and Mo inhibiting high-temperature grain growth. The matrix of 90TiB2+10(TiC + B4C + Co + Mo) recipe achieved 94.7 % relative density and a hardness of 31.97 GPa. Moreover, adding polyvinyl butyral (PVB) assists in creating gas evacuation channels during the sintering process. The research also reveals the reaction between TiC and B4C, forming (TiMoB)C with molybdenum, while the eutectic Co–Mo alloy dissolves into borides, promoting densification and forms dense core-rim structures.

Are Ecosystem Engineering Traits Fixed or Flexible: A Study on Clonal Expansion Strategies in Co-occurring Dune Grasses

Many vegetated coastal ecosystems are formed through ecosystem engineering by clonal vegetation. Recent work highlights that the spatial shoot organization of the vegetation determines local sediment accretion and subsequently emerging landscape morphology. While this key engineering trait has been found to differ between species and prevailing environmental conditions, it remains unknown how the interplay of both factors drive shoot organization and therefore landscape morphology. Here, we compared the spatial shoot organization of young, clonally expanding plants of the two dominant European dune grass species: sand couch (Elytrigia juncea) and marram grass (Ammophila arenaria) across a range of coastal dune environments (from Denmark to France). Our results reveal that, on average, sand couch deployed a more dispersed shoot organization than marram grass, which has a patchy (Lévy-like) organization. Whereas sand couch exhibited the same expansion strategy independent of environmental conditions, marram grass demonstrated a large intraspecific variation which correlated to soil organic matter, temperature and grain size. Shoot patterns ranged from a clumped organization correlating to relatively high soil organic matter contents, temperature and small grain sizes, to a patchy configuration with intermediate conditions, and a dispersed organization with low soil organic matter, temperature and large grain size. We conclude that marram grass is flexible in adjusting its engineering capacity in response to environmental conditions, while sand couch instead follows a fixed expansion strategy, illustrating that shoot organization results from the interaction of both species-specific and environmental-specific trait expression.

The effect of plasma-assisted ball milling on preparation and sintering behavior of (Zr0.1429Hf0.1429Ce0.1429Y0.2857La0.2857)O2-δ high entropy fluorite oxide

The sintering process of high entropy fluorite oxide ceramics prepared by the conventional solid-phase reaction method suffers from high single-phase synthesis temperature, low densities, and abnormal grain growth. To improve the sintering characteristics of high entropy fluorite oxide ceramics, the oxide mixture was dealt with dielectric barrier discharge plasma-assisted ball milling. The samples were analyzed using XRD, SEM, TEM, TG/DTG, visual high-temperature deformation analyzer, and nanoindentation meter. The results show that the plasma field activates the raw material powder and promotes powder finer. The rapid heating effect of the plasma during the ball milling process causes micro-area sintering and micro-area melting on the powder surface, which increases the active sites of the solid phase reaction of the material, accelerates the mass transfer process, and improves the sintering activity. Compared with conventional ball milling, plasma-assisted ball milling reduces the single-phase synthesis temperature of high entropy ceramics from 1500 °C to 1300 °C. The sintered ceramic pellets have intact grain growth, no noticeable abnormal grain growth, and improved density and mechanical properties.

Various temperature effects on spikelet growth in hulless oat during grain-filling stage

Temperature conditions affect growth and grain development during the grain-filling stage, but a comprehensive analysis of oat subjected to different temperatures during grain development has not been studied. In this study, an integrated physiological and proteomic examination of oat spikelets was performed to analyze the influence of five different day-time temperatures on stress-relative parameters and grain development. Physiological analysis showed decrease of total chlorophyll, shoot dry weight and spikelet shape development and increased activation of MDA, soluble sugar and antioxidant enzymes, with increase of temperatures. However, considering major grain yield components and storage materials, there should be an optimum temperature during ripening period. The result of proteomic analysis showed significantly high expressions of stress-related gene in high temperature treatment and grain storage materials in optimum temperature. Our findings indicate that temperature conditions during the grain-filling period exert a major influence on yield potential.

Exploring the optimal two-step selenization process to enhance the performance of ionic liquid solution based Cu2ZnSn(S,Se)4 thin film solar cells

Two-step selenization process has been proved to control Cu 2 ZnSn(S,Se) 4 (CZTSSe) crystallization growth, helping to fabricate a homogeneous large-grain structure of CZTSSe absorber. The two-step selenization process is usually composed of the low-temperature nucleation (LT) and high-temperature grain growth reaction (HT) processes. Here, an exploration of optimizing the annealing conditions at each step in the two-step process is reported to obtain the excellent structure of ionic liquid solution based Cu 2 ZnSn(S,Se) 4 absorber, boosting performance of the solar cell. Based on the basic requirement of an absorber candidate for solar cells (the compact films), three effective kinds of two-step process are confirmed (LT400–10&HT540–10, LT400–10&HT550–10, and LT400–10&HT560–10). We further explore the other properties of sample prepared by one-step and these three kinds of two-step process, respectively, and the optimal two-step process can be identified as LT400–10&HT550–10, which also confirms a homogeneous large-grain structure of CZTSSe absorber. Finally, CZTSSe solar cell with the highest efficiency of 9.24% can be achieved, which can be improved 67% than one by one-step annealing process (5.54%). • The detail optimization of annealing conditions at each step in the two-step selenization process is explored. • Homogeneous large-grain structure of Cu 2 ZnSn(S,Se) 4 absorber can be fabricated at the optimal two-step selenization condition. • The best efficiency of corresponding device can be obtained to be 9.24%, increased by 67% compared with one-step process.

Effect of creep parameters on the steady-state flow stress of pure metals processed by high-pressure torsion

The correlation between the flow stress and grain size for severely deformed metals remains undefined because the conventional Hall-Petch relationship ignores the expected contributions from thermally-activated phenomena in nanomaterials and also it fails to explain the reported strain softening of metals having low melting temperatures. In this study, the contribution of thermally-activated creep mechanisms to the room temperature flow stress is evaluated for 31 pure metals processed by high-pressure torsion. The steady-state grain size and the hardness of these metals are first compared to theoretical predictions from high temperature creep mechanisms. It is shown that these mechanisms are not able to predict the flow stress, although the data from metals with low melting temperatures fall close to the theoretical prediction for high-temperature grain boundary sliding suggesting a possible explanation for the unusual softening of these metals. Nevertheless, a detailed analysis demonstrates that a modified model for grain boundary sliding at low temperature provides the capability of correctly predicting the flow stresses for metals having both high and low melting temperatures. The results confirm the significance of thermally-activated phenomena in determining the flow stress of nanomaterials processed by severe plastic deformation.

Ruthenium doped Ge2Sb2Te5 nanomaterial as fast speed phase-change materials with good thermal stability

Ge2Sb2Te5 (GST) as phase-change material has the advantage of good thermal stability and long cycle life, however large power consumption and lower phase change speed partly limit large-scale application for phase-change materials (PCM). In this paper, a comprehensive research is investigated on Ru doped GST phase-change material, from properties to performances for PCM application. Ru doping can efficiently improve the thermal stability of GST alloy and the thickness change of Ru0.05(GST)0.95 film is 3.3%. In addition, high 10-year data retention temperature (∼151 °C) and small crystal grain reflect the advantages of data retention and low power consumption for Ru0.05(GST)0.95 film. Furthermore, the structure characteristics show the stable face-centred cubic structure at crystalline state after annealing. As for electrical properties, Ru0.05(GST)0.95-based PCM cell shows excellent reversible SET-RESET properties with a suitable operation window and good endurance up to 106 electrical cycles with a resistance ratio of about 10. And also, it has a dramatically lower power consumption of 1.46 × 10-11 J compared with GST-based cell (4.76 × 10-10 J), making it a promising material for the Internet of Things (IOT) field applications.

Effect of morphology and content of nano-C on grain growth behavior of copper matrix composites

This study compares high-temperature grain growth behavior in copper matrix composites containing nano-carbons in the form of fullerenes, carbon nanotubes (CNTs), and graphene to investigate the effect of volume fraction and shape of nano-carbon reinforcement on grain growth suppression. The grain growth was significantly suppressed when the nano-carbon content was 5 vol%, but the suppression efficiency was reduced when nano-carbon particle loading increased above 20 vol%. Furthermore, CNTs induced better grain growth suppression than fullerenes and graphene. Grain growth was observed both near the nano-carbon interfaces and in the bulk matrix. The poor wetting ability between copper and the nano-carbons accelerates lattice diffusion at the reinforcement interface. Owing to differences in the thermal expansion coefficients and elastic moduli between copper and the nano-carbons, due to the presence of the reinforcement, stress distribution will be inhomogeneous. In composites containing discontinuous reinforcement, the stress is concentrated at the tip of the reinforcement and at its minimum at the center of the reinforcement. Inhomogeneous stress fields are formed in the far away from the reinforcement, which in turn causes the suppression of overall grain growth in the composites.

Deformation mechanisms in ultrafine-grained metals with an emphasis on the Hall–Petch relationship and strain rate sensitivity

Ultrafine-grained materials display almost no strain hardening, an enhanced strain rate sensitivity and grain boundary offsets during plastic deformation. It is expected that dislocation climb is active in order to enable prompt recovery. The present analysis proposes a deformation mechanism that includes these effects and follows from the mechanism for high temperature grain boundary sliding. This mechanism predicts the relationship between strain rate, flow stress, grain size, temperature and basic material properties such as the Burgers vector modulus, the shear modulus and the grain boundary diffusion coefficient. The model may be used to estimate the final grain size achieved by severe plastic deformation and the strain rate sensitivity. An analysis shows that the predicted behavior agrees with the data from multiple experimental investigations and provides a good estimate of the Hall–Petch slope for different materials which includes breakdown and inverse Hall–Petch behavior under some conditions. The incorporation of a threshold stress provides an opportunity to predict the relationship between flow stress and grain size for a broad range of grain sizes, strain rates and temperatures. An excellent agreement is observed between the predictions of the model and experimental data for Al, Cu, Fe (α), Fe(γ), Mg, Ni, Ti and Zn.

(Invited) Brief Overview of Current French Hydrogen Research Activities, Focus on SOFC Materials Development

Twenty years ago, the French scientific community working in the field of hydrogen, started to federate under the leadership of the CNRS. It took the form of successive Research Grouping (GdR) bringing together experts in solid oxide fuel cell (SOFC), proton exchange polymer membrane (PEMFC) fuel cells, hydrogen storage and systems mainly from CNRS but also from CEA. These GdRs promoted and structured an interdisciplinary field of research with excellent results.Since January 1st of 2020, the CNRS community has formed the Research network on Hydrogen energy (FRH2) based on the active nucleus of the former GDR laboratories (28 laboratories) with about 90 full-time equivalent positions including researchers and professors, without including technical staff, students, doctoral students and post-docs. A new organization, "from material to system", more visible from industries has been set up around four main technical axes, the production of hydrogen, its storage, and its conversion into electricity for mobile and stationary applications and around 2 transversal axes, education and technological platforms. The first part of the presentation will give a brief overview of this french CNRS research network on hydrogen energy including some highligts for each axes.The second part will be dedicated to the development of materials used in solid oxide fuel cells (SOFC) and more precisely to the ceramic electrolyte. Electrochemical properties of the materials used in SOFC are governed by the defects within the material and limited by the microstructure and the transport mechanisms of charge carrier at the interfaces. Thus, the optimization of the microstructure of the material via accurate monitoring of the synthesis and temperature treatment steps could enhance the conduction properties of existing materials. The usual objective for electrolyte material is to reach a total conductivity level above 10-2 S/cm for operating temperatures below 600°C. Actually, working at low temperature would prevent premature aging of SOFC performance.BCZY type proton conducting electrolyte such as BaCe0.8Zr0.1Y0.1O3-δ has gained a great attention as one of the most promising candidate for intermediate temperature solid oxide fuel cells, due to the combination of a high bulk conductivity associated to a chemical stability [1]. However, some of challenges to manufacture a dense BCZY ceramic are the high sintering temperature typically 1500 to 1600°[2], and the long processing duration in conventional method which can damage the material and cause barium evaporation resulting in a decrease of electrochemical properties.Part of this talk is focused on BaCe0.8Zr0.1Y0.1O3-δ showing properties which are a compromise between the high proton conductivity of BCY and the stability of BZY. The limiting factors are the high sintering temperature (≈1600°C) and intrinsic grain boundaries resistance.The cold sintering process (CSP) is used to reduce the sintering temperature. In this technic, derived from the hydrothermal method, BCZY powder mixed with a small volume of liquid phase (3-30 wt%), is simultaneously pressed (at 50 to 500 MPa) and heat treated during a short time period (1-60 min) at low temperatures (100-200°C), leading to dense pellets.This study deals with the influence of synthesis conditions using the auto combustion and CSP on the microstructure and conductivity. With a calcination temperature of 1000°C and an optimized CSP treatment, a relative density above 93% can be obtained at only 1200°C. We will show also the influence of the cold sintering process (CSP) on the conductivity. Compared to conventional sintering process at about 1600°C, high conductivity level of 10-2 S/cm is obtained at 400°C (figure 1) using CSP process combined with a 1200°C annealing step.[1] K. Thabet, M. Devisse, E. Quarez, O. Joubert, et A. Le Gal La Salle, "Influence of the autocombustion synthesis conditions and the calcination temperature on the microstructure and electrochemical properties of BaCe0.8Zr0.1Y0.1O3−δ electrolyte material", Solid State Ionics, vol. 325, 2018, p. 48-56,[2] F. Iguchi, T. Yamada, N. Sata, T. Tsurui, et H. Yugami, "The influence of grain structures on the electrical conductivity of a BaZr0.95Y0.05O3 proton conductor", Solid State Ionics, vol. 177, no 26, 2006, p. 2381-2384 Figure 1

Nanoparticles Study on the Indosinian Xiaomei Shear Zone in the Hainan Island, China: Implication to Developmental Stage and Formation Mechanism of Nanoparticles in a Fault Zone

Nanoparticles are widely observed in the natural shear zone and experimental slip faults, which can lubricate the fault and significantly reduce the friction coefficient during seismic slip. But it is still not clear how the nanoparticles develop during the process of sliding. Clarifying the development stage of nanoparticles in a fault zone is critical to understanding the formation mechanisms of nanoparticles and the mechanism of fault weakening from a nanoperspective. In this study, four types of nanoparticles were found in the Indosinian Xiaomei shear zone, including spherical nanoparticles, rod-like nanograins and their aggregations. Ultramicroscopic analyses indicate that polished patches are highly smooth and composed of tightly packed spherical nanoparticles and well orientated rod-like nanograins during slip at high velocities. Meanwhile, the dome nanoparticles were formed by the calcite thermal decomposition due to frictional heat during highspeed sliding. The polygonal grooves are possibly related to high temperature (>900 °C) grain boundary sliding deformation mechanisms. However, the porous and rough surfaces are accompanied by a series of holes and parallel “scratches” during a subsequent low-velocity stage. To ascertain the chemical composition of these nanoparticles, the energy dispersive spectrometer (EDS) test were conducted. The results suggest that materials rich in Fe, MgO and wollastonite are likely to form the rod-like nanograins, while materials rich in SiO2 are likely to form the spherical nanoparticles.

Imparting high-temperature grain stability to an Al-Mg alloy

Al alloys, despite their excellent strength-to-weight ratio, cannot be used at elevated temperatures because of microstructural instability owing to grain growth and precipitate coarsening, thus, leading to a drastic loss in their strength. In this work, we have attempted to address the issue of grain growth by introducing in-situ formed polymer derived ceramics in an Al-Mg alloy. A stable grain structure with minimal loss in hardness when exposed to 450°C and 550°C for 1 hour was obtained due to the particle pinning of the grain boundaries by the Zener mechanism.

Mechanism of Variation in High-Temperature Grain Stability of Aluminum in Dissimilar Friction Stir Welds

Abstract In the dissimilar Friction Stir Welding (FSW) of aluminum to titanium, a large fraction of titanium particles is inhomogeneously distributed in the weld nugget and their distribution is highly complex. Such a distribution can have an immense influence on the grain stability of the weld nugget, which decides its mechanical properties at the high temperatures experienced in critical applications. The present investigation highlights the variation in grain structure at the top surface and center of the weld nugget. The results show that the microstructure at the surface of the weld contains a higher fraction of fine titanium particles, refined grains of aluminum and high-angle grain boundaries, and a lower intensity of shear texture components when compared to the center of the weld nugget. The variation in the grain stability of the weld was correlated with the qualitative variation in the strain rate and temperature in the weld. It is proposed that the formation and distribution of a high fraction of fine titanium particles results in superior grain stability of aluminum at the surface of the weld due to arrest of the grain boundary mobility against grain growth. This mechanism and methodology can be applied in developing metal matrix composites with superior mechanical properties as well.

Strength through disorder

Metallurgy Jet turbine blades and other objects with ultrahigh strength at high temperatures are made of special alloys that are often grown as costly single crystals to help avoid failure. Yang et al. discovered that adding a small amount of boron in a nickel-cobalt-iron-aluminum-titanium alloy creates an ultrahigh-strength material. Critically, the alloy has a nanoscale-disordered interface in between crystal grains that substantially improves the ductility while preventing high-temperature grain coarsening. This alloy design creates attractive high-temperature properties for various applications. Science , this issue p. [427][1] [1]: /lookup/doi/10.1126/science.abb6830