Microstructure and mechanical properties of heat-treated Ti-5Al-2Sn-2Zr-4Mo-4Cr

The effects of heat treatment parameters on the microstructure,and mechanical properties and fractured morphology of Ti-5Al-2Sn-2Zr-4Mo-4Cr with the equiaxed,bi-modal and Widmanst？tten microstructures were investigated.The heating temperatures for obtaining the equiaxed,bi-modal and Widmanst？tten microstructures were 830,890 and 920 °C,respectively,followed by furnace cooling at a holding time of 30 min.The volume fraction of primary α phase decreased with increasing the heating temperature,which was 45.8% at 830 °C,and decreased to 15.5% at 890 °C,and then the primary α phase disappeared at 920 °C during furnace cooling.The variation of volume fraction of primary α phase in air cooling is similar to that in furnace cooling.The increase in heating temperature and furnace cooling benefited the precipitation and growth of the secondary α phase.The equiaxed microstructure exhibited excellent mechanical properties,in which the ultimate strength,yield strength,elongation and reduction in area were 1035 MPa,1011 MPa,20.8% and 58.7%,respectively.The yield strength and elongation for the bi-modal microstructure were slightly lower than those of the equiaxed microstructure.The Widmanst？tten microstructure exhibited poor ductility and low yield strength,while the ultimate strength reached 1078 MPa.The dimple fractured mechanism for the equiaxed and bi-modal microstructures proved excellent ductility.The coexistence of dimple and intercrystalline fractured mechanisms for the Widmanst？tten microstructure resulted in the poor ductility.

Microstructure investigation of a new type super high strength aluminum alloy at different heat-treated conditions

As a structural material with low density and high strength, super-highstrength aluminum alloys have a future for wide application. However, its poor stress corrosionresistance (SCC) restricts further development. In present, retrogression and re-ageing (RRA)treatment, which can improve both strength and SCCR of 7XXX series alloy, is a best method to solvethis problem. The effect of RRA treatment on the microstructure evolution of a new type lowfrequency electric-magnetic casting Al-9.OZn-2.45Mg-2.2Cu-0.15Zr alloy was investigated using DSCand TEM technologies. The results show that the typical microstructure of the alloy at T6 conditionis characterized by both fine eta' and GP zone homogeneously distributed in the matrix andcontinuous r) particles occurred on the grain-boundary. After RRA treatment, the matrixprecipitations are mainly fine and dispersed eta' and eta phases, being coarser and more stable thanthat from T6 temper. While, the grain-boundary microstructure is very close to that resulting fromT73 temper. High retrogression temperature and long retrogression time leads to a more stablemicrostructure after re-ageing.

Heat-treated microstructure and mechanical properties of laser solid forming Ti-6Al-4V alloy

The effects of heat treatment on the microstructure and mechanical properties of laser solid forming （LSF） Ti-6Al-4V alloy were investigated The influences of the temperature and time of solution treatment and aging treatment were analyzed. The results show that the microstructure of LSFed samples consists of Widmanstatten α laths and a little acicular in columnar prior β grains with an average grain width of 300 μm, which grow epitaxiaUy from the substrate along the deposition direction （27）. Solution treatment had an important effect on the width, aspect ratio, and volmne fraction of primary and secondary a laths, and aging treatment mainly affects the aspect ratio and volume fraction of primary α laths and the width and volume fraction of secondary a laths. Globular a phase was first observed in LSFed samples when the samples were heat treated with solution treatment （950℃, 8 h/air cooling （AC）） or with solution treatment （950℃, 1 h/AC） and aging treatment （550℃, above 8 h/AC）, respectively. The coarsening and globularization mechanisms of a phase in LSFed Ti-6Al-4V alloy during heat treatment were presented. To obtain good integrated mechanical properties for LSFed Ti-6Al-4V alloys, an optimized heat treatment regimen was suggested.

RAPID NONDESTRUCTIVE TESTING OF HEAT-TREATMENT QUALITY OF 2014 ALUMINIUM ALLOY

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Microstructural evolution of a heat-treated H23 tool steel

The microstructure and the stability of carbides after heat treatments in an H23 tool steel were investigated. The heat treatments consisted of austenization at two different austenizing temperatures （1100℃ and 1250℃）, followed by water quenching and double-aging at 650℃, 750℃, and 800℃with air cooling between the first and second aging treatments. Martensite did not form in the as-quenched micro- structures, which consisted of a ferrite matrix, M6C, M7C3, and MC carbides. The double-aged microstructures consisted of a ferrite matrix and MC, M6C, M7C3, and M23C6 carbides. Secondary hardening as a consequence of secondary precipitation of fine M2C carbides did not occur. There was disagreement between the experimental microstructure and the results of thermodynamic calculations. The highest double-aged hardness of the H23 tool steel was 448 HV after austenization at 1250℃ and double-aging at 650℃, which suggested that this tool steel should be used at temperatures below 650℃.

Study of Frequency Effects on Hardness Profile of Spline Shaft Heat-Treated by Induction

This paper is devoted to the study of frequency effects on hardness profile of AISI 4340 spline shaft heat-treated by induction through an extensive 3D finite element method simulation and structured experimental investigation. Based on coupled electromagnetic and thermal fields analysis, the 3D model is used to estimate the temperature distribution and the hardness profile. The proposed study examines the hardening process parameters, such as frequency, induced current density and heating time, known to have an influence on hardened surface and builds the simulation model step by step. The established model can provide not only an accurate prediction of temperature distribution and hardness profile but also a comprehensive analysis of machine parameters effects, especially the frequency. The numerical results achieved by this model are good and present a great agreement to the experimental data.

Mechanical Response and Energy Dissipation Analysis of Heat-Treated Granite Under Repeated Impact Loading

The mechanical behaviors and energy dissipation characteristics of heat-treated granite were investigated under repeated impact loading.The granite samples were firstly heat-treated at the temperature of 20℃,200℃,400℃,and 600℃,respectively.The thermal damage characteristics of these samples were then observed and measured before impact tests.Dynamic impact compression tests finally were carried out using a modified split-Hopkinson pressure bar under three impact velocities of 12 m/s,15 m/s,and 18 m/s.These test results show that the mineral composition and the main oxides of the granite do not change with these treatment temperatures.The number of microcracks and microvoids decreases in the sample after 200℃ treatment.The mechanical properties of a sample after 600℃ treatment were rapidly deteriorated under the same impact velocity.The average of peak stress is much smaller than those after 20℃,200℃ and 400℃ treatments.The heat-treated samples have an energy threshold each.When the dissipated energy of a sample under a single impact is less than this threshold,the repeated impacts hardly lead to further damage accumulation even if its total breakage energy dissipation(BED)density is large.Under the same number of repeated impacts,the cumulative BED density of a sample after 600℃ treatment is the largest and its damage evolves most quickly.The total BED density of the sample after 200℃ treatment is the highest,which implies that this sample has better resistance to repeated impact,thus having less crack initiation and growth.

Evolution and distribution of Al_2Sm phase in as-extruded AZ61-xSm magnesium alloys during semi-solid isothermal heat-treatment

The evolution and distribution of Al2Sm phase in as-extruded AZ61-xSm（x=0, 1.5, 2.0 and 2.5, mass fraction, %） magnesium alloys during semi-solid isothermal heat treatment were investigated. The results showed that when as-extruded AZ61 magnesium alloys were modified with Sm, the smaller and rounder grains were obtained during semi-solid isothermal heat treatment. When the Sm content is 2.0%（mass fraction）, the average size of the globular grains reached the smallest value of 90 μm. Although a few Al2Sm particles existed in the α-Mg grains, most of Al2Sm particles solidified at the edge of the globular grains with the width of 20 μm. These phenomena are mainly attributed to the forces acting on Al2Sm particles in front of the solid-liquid interface, leading to Al2Sm particles accumulating at the solid-liquid interface and then solidifying at the edge of the globular grains in the quenching process.

Corrosion behaviour of thixoformed and heat-treated ZA27 alloys in NaCl solution

The influence of corrosion on the microstructure of thixoformed and heat-treated ZA27 alloys was investigated. The microstructure of ZA27 alloy was affected by heat treatment. The process of electrochemical corrosion occurs in both ZA27 alloys through the area of r/phase. According to the results of immersion test and electrochemical measurements, the corrosion rate of the thixoformed ZA27 alloy is at least 50% lower than that of the thixoformed and thermally processed alloy. This indicates the unfavourable influence of applied heat treatment （T4 regime） on the corrosion resistance of the thixoformed ZA27 alloy.

Simulating Tests for the Heat-treatment of Ancient Bronze Mirrors

In academic circles there are different views on question if existed heat-treatment technique for ancient bronze mirrors in China. On this question a series of simulating tests were carried out. By using quenching and tempering the same structure as in ancient bronze mirrors was obtained, therefore, it was proved that Chinese ancient bronze mirrors underwent heat-treatment. Meanwhile the view that the tempered structure of bronze at high temperature is analogous to its quenched structure at high temperature was corrected.

Heat Post-Treatment to Reduce Thickness Swelling of Particleboard from Fast-Growing Poplars

According to the high thickness swelling and low dimensional stability of Poplars particleboard, this paper studied the effect of heat post-treatment on the board properties. The results indicated that the post-treatment could be a very effective way to produce dimensinaly stable fast-growing poplars particleboard. The thickness swelling of the board decreased with increasing the time and temperatures of post-heat treatment. So under190℃, being treated for 15 min., the total thickness swelling (TS1) of the board was 8.96%, reduced by 22.88%. The irreversible thickness swelling (TS2) was also reduced with the post-treatment of 190 ℃ or 220℃; The reversible thickness swelling (TS3) was not signifcantly changed when the time of treatment increased up to 25 min. under 190℃.

Influence of heat treatment on microstructure,mechanical and corrosion behavior of WE43 alloy fabricated by laser-beam powder bed fusion

Magnesium(Mg)alloys are considered to be a new generation of revolutionary medical metals.Laser-beam powder bed fusion(PBF-LB)is suitable for fabricating metal implants withpersonalized and complicated structures.However,the as-built part usually exhibits undesirable microstructure and unsatisfactory performance.In this work,WE43 parts were firstly fabricated by PBF-LB and then subjected to heat treatment.Although a high densification rate of 99.91%was achieved using suitable processes,the as-built parts exhibited anisotropic and layeredmicrostructure with heterogeneously precipitated Nd-rich intermetallic.After heat treatment,fine and nano-scaled Mg24Y5particles were precipitated.Meanwhile,theα-Mg grainsunderwent recrystallization and turned coarsened slightly,which effectively weakened thetexture intensity and reduced the anisotropy.As a consequence,the yield strength and ultimate tensile strength were significantly improved to(250.2±3.5)MPa and(312±3.7)MPa,respectively,while the elongation was still maintained at a high level of 15.2%.Furthermore,the homogenized microstructure reduced the tendency of localized corrosion and favoredthe development of uniform passivation film.Thus,the degradation rate of WE43 parts was decreased by an order of magnitude.Besides,in-vitro cell experiments proved their favorable biocompatibility.

MXene/Cellulose Composite Cloth for Integrated Functions(if‑Cloth)in Personal Heating and Steam Generation

Given the abundant solar light available on our planet,it is promising to develop an advanced fabric capable of simultaneously providing personal thermal management and facilitating clean water production in an energy-efficient manner.In this study,we present the fabrication of a photothermally active,biodegradable composite cloth composed of titanium carbide MXene and cellulose,achieved through an electrospinning method.This composite cloth exhibits favorable attributes,including chemical stability,mechanical performance,structural flexibility,and wettability.Notably,our 0.1-mm-thick composite cloth(RC/MXene IV)raises the temperature of simulated skin by 5.6℃when compared to a commercially available cotton cloth,which is five times thicker under identical ambient conditions.Remarkably,the composite cloth(RC/MXene V)demonstrates heightened solar light capture efficiency(87.7%)when in a wet state instead of a dry state.Consequently,this cloth functions exceptionally well as a high-performance steam generator,boasting a superior water evaporation rate of 1.34 kg m^(-2)h^(-1)under one-sun irradiation(equivalent to 1000 W m^(-2)).Moreover,it maintains its performance excellence in solar desali-nation processes.The multifunctionality of these cloths opens doors to a diverse array of outdoor applications,including solar-driven water evaporation and personal heating,thereby enriching the scope of integrated functionalities for textiles.

The ZmHSF08-ZmUGT92A1 module regulates heat tolerance by altering reactive oxygen species levels in maize

GTs(Glycosyltransferases)are important in plant growth and abiotic stresses.However,its role in maize heat response is far from clear.Here,we describe the constitutively expressed UDP-glycosyltransferase ZmUGT92A1,which has a highly conserved PSPG box and is localized in chloroplasts,is induced under heat stress.Functional disruption of ZmUGT92A1 leads to heat sensitivity and reactive oxygen species accumulation in maize.Metabolomics analysis revealed that ZmUGT92A1 affected multiple metabolic pathways and altered the metabolic homeostasis of flavonoids under heat stress.In vitro assay showed ZmUGT92A1 exhibits glycosyltransferase activity on flavonoids and hormones.Additionally,we identified a rapidly heat-induced transcription factor,ZmHSF08,which can directly bind and repress the promoter region of ZmUGT92A1.The ZmHSF08 overexpression line exhibits heat sensitivity and reactive oxygen species accumulation.These findings reveal that the ZmHSF08-ZmUGT92A1 module plays a role in heat tolerance in maize and provide candidate strategies for the development of heat-tolerant varieties.

Photoluminescence Spectra of Post-heat-treated Porous Silicon

Porous silicon prepared by pulse electro-etching is heat-treatedin O_2 atmosphere with an enhancement of its PI. peak and animprovement of its PL stability. The PL peak of a sample poroussilicon treated in O_2 atmosphere at 1000 ℃ presents itself a three--peak structure and, compared with an un-- heat--treated sample,there exists blue shift of ～ 40 nm.

Enhanced coercivity and remanence of PrCo_5 nanoflakes prepared by surfactant-assisted ball milling with heat-treated starting powder

PrCo5 nanoflakes with strong texture and high coercivity of 8.15 kOe were prepared by surfactant-assisted ball milling with heat-treated starting powder. The thickness and length of the as-milled nanoflakes are mainly in the ranges of 50–100 nm and 0.5–3 μm, respectively. The x-ray diffraction patterns demonstrate that the heat treatment can increase the single phase and crystallinity of the PrCo5 compound, and combined with the demagnetization curves, indicate that the single phase and crystallinity are important for preparing high-coercivity and strong-textured rare earth permanent magnetic nanoflakes. In addition, the coercivity mechanism of the as-milled PrCo5 nanoflakes is studied by the angle dependence of coercivity for an aligned sample and the field dependence of coercivity, isothermal（IRM） and dc demagnetizing（DCD）remanence curves for an unaligned sample. The results indicate that the coercivity is dominated by co-existing mechanisms of pinning and nucleation. Furthermore, exchange coupling and dipolar coupling also co-exist in the sample.

A NEW HEAT-TREATMENT PROCESS FOR 2014 ALUMINUM ALLOY AND ITS MECHANISM

The plan of heat-treatment process for 2014Al alloy is designed using orthogonal method, the heat-treatment experiments are made and the mechanical properties are tested according to the designed plan. The effect of solid solution temperature, ageing temperature, ageing time on microscopic mechanism of the mechanical properties of the 2014Al alloy is studied using microscope, transmission electron microscope. The best heat treatment process of the 2014Al alloy is developed. The experimental results indicate that the strength σb, yield stress σ0.2, percentage elongation δ of the alloy reach separately 490～500 MPa, 450～490 MPa, 10～12％ adopting the new heat treatment process. Compared with GB, the strength increases 20～30％, the percentage elongation increases 30～40％. The mechanism of the new heat-treatment process is also discussed.

Personal Thermal Management by Radiative Cooling and Heating

Maintaining thermal comfort within the human body is crucial for optimal health and overall well-being.By merely broadening the setpoint of indoor temperatures,we could significantly slash energy usage in building heating,ventilation,and air-conditioning systems.In recent years,there has been a surge in advancements in personal thermal management(PTM),aiming to regulate heat and moisture transfer within our immediate surroundings,clothing,and skin.The advent of PTM is driven by the rapid development in nano/micro-materials and energy science and engineering.An emerging research area in PTM is personal radiative thermal management(PRTM),which demonstrates immense potential with its high radiative heat transfer efficiency and ease of regulation.However,it is less taken into account in traditional textiles,and there currently lies a gap in our knowledge and understanding of PRTM.In this review,we aim to present a thorough analysis of advanced textile materials and technologies for PRTM.Specifically,we will introduce and discuss the underlying radiation heat transfer mechanisms,fabrication methods of textiles,and various indoor/outdoor applications in light of their different regulation functionalities,including radiative cooling,radiative heating,and dual-mode thermoregulation.Furthermore,we will shine a light on the current hurdles,propose potential strategies,and delve into future technology trends for PRTM with an emphasis on functionalities and applications.

Pre‑hatch thermal manipulation of embryos and post‑hatch baicalein supplementation mitigated heat stress in broiler chickens

Background High environmental temperatures induce heat stress in broiler chickens,affecting their health and pro-duction performance.Several dietary,managerial,and genetics strategies have been tested with some success in mitigating heat stress(HS)in broilers.Developing novel HS mitigation strategies for sustaining broiler production is critically needed.This study investigated the effects of pre-hatch thermal manipulation(TM)and post-hatch baica-lein supplementation on growth performance and health parameters in heat-stressed broilers.Results Six hundred fertile Cobb 500 eggs were incubated for 21 d.After candling on embryonic day(ED)10,238 eggs were thermally manipulated at 38.5℃ with 55%relative humidity(RH)from ED 12 to 18,then transferred to the hatcher(ED 19 to 21,standard temperature)and 236 eggs were incubated at a controlled temperature(37.5℃)till hatch.After hatch,180-day-old chicks from both groups were raised in 36 pens(n=10 birds/pen,6 replicates per treatment).The treatments were:1)Control,2)TM,3)control heat stress(CHS),4)thermal manipulation heat stress(TMHS),5)control heat stress supplement(CHSS),and 6)thermal manipulation heat stress supplement(TMHSS).All birds were raised under the standard environment for 21 d,followed by chronic heat stress from d 22 to 35(32–33℃ for 8 h)in the CHS,TMHS,CHSS,and TMHSS groups.A thermoneutral(22–24℃)environment was maintained in the Control and TM groups.RH was constant(50%±5%)throughout the trial.All the data were analyzed using one-way ANOVA in R and GraphPad software at P<0.05 and are presented as mean±SEM.Heat stress significantly decreased(P<0.05)the final body weight and ADG in CHS and TMHS groups compared to the other groups.Embryonic TM significantly increased(P<0.05)the expression of heat shock protein-related genes(HSP70,HSP90,and HSPH1)and antioxidant-related genes(GPX1 and TXN).TMHS birds showed a significant increment(P<0.05)in total cecal volatile fatty acid(VFA)concentration compared to the CHS birds.The cecal microbial analysis showed significant enrichment(P<0.05)in alpha and beta diversity and Coprococcus in the TMHSS group.Conclusions Pre-hatch TM and post-hatch baicalein supplementation in heat-stressed birds mitigate the detrimental effects of heat stress on chickens’growth performance,upregulate favorable gene expression,increase VFA produc-tion,and promote gut health by increasing beneficial microbial communities.

Optimum Profiles of Endwall Contouring for Enhanced Net Heat Flux Reduction and Aerodynamic Performance

Successfully utilized non-axisymmetric endwalls to enhance turbine efficiencies(aerodynamic and turbine inlet temperatures)by controlling the characteristics of the secondary flow in a blade passage.This is accomplished by steady-state numerical hydrodynamics and deep knowledge of the field of flow.Because of the interaction between mainstream and purge flow contributing supplementary losses in the stage,non-axisymmetric endwalls are highly susceptible to the inception of purge flow exit compared to the flat and any advantage rapidly vanishes.The conclusions reveal that the supreme endwall pattern could yield a lowering of the gross pressure loss at the design stage and is related to the size of the top-loss location being productively lowered.This has led to diminished global thermal exchange lowered in the passage of the vane alone.The reverse flow adjacent to the suction side corner of the endwall is migrated farther from the vane surface,as the deviated pressure spread on the endwall accelerates the flow and progresses the reverse flow core still downstream.The depleted association between the tornado-like vortex and the corner vortex adjacent to the suction side corner of the endwall is the dominant mechanism of control in the contoured end wall.In this publication,we show that the non-axisymmetric endwall contouring by selective numerical shape change method at most prominent locations is advantageous in lowering the thermal load in turbines to augment the net heat flux reduction as well as the aerodynamic performance using multi-objective optimization.