Hot deformation behavior of microstructural constituents in a duplex stainless steel during high-temperature straining

The hot deformation characteristics of 1.4462 duplex stainless steel （DSS） were analyzed by considering strain partitioning between austenite and ferrite constituents. The individual behavior of ferrite and austenite in microstructure was studied in an iso-stress condition. Hot compression tests were performed at temperatures of 800-1100~C and strain rates of 0.001-1 s-1. The flow stress was modeled by a hyperbolic sine constitutive equation, the corresponding constants and apparent activation energies were determined for the studied alloys. The constitutive equation and law of mixture were used to measure the contribution factor of each phase at any given strain. It is found that the contribution factor of ferrite exponentially declines as the Zener-HoUomon parameter （Z） increases. On the contrary, the austenite contribution polynomially increases with the increase of Z. At low Z values below 2.6. x 1015 （lnZ---35.5）, a negative contribution factor is determined for austenite that is attributed to dynamic recrystallization. At high Z values, the contribution factor of austenite is about two orders of magnitude greater than that of ferrite, and therefore, austenite can accommodate more strain. Microstructural characterization via electron back-scattered diffraction （EBSD） confirms the mechanical results and shows that austenite recrystallization is possible only at high temperature and low strain rate.

Dynamic recrystallization and precipitation in high manganese austenitic stainless steel during hot compression

Dynamic recrystallization and precipitation in a high manganese austenitic stainless steel were investigated by hot compression tests over temperatures of 950-1150~C at strain rates of 0.001 s-1-1 s-1. All the flow curves within the studied deformation regimes were typ- ical of dynamic recrystallization. A window was constructed to determine the value of apparent activation energy as a function of strain rate and deformation temperature. The kinetics of dynamic recrystallization was analyzed using the Avrami kinetics equation. A range of apparent activation energy for hot deformation from 303 kJ/mol to 477 kJ/mol is obtained at different deformation regimes. Microscopic characterization confirms that under a certain deformation condition （medium Zener-Hollomon parameter （Z） values）, dynamic recrystalliza- tion appears at first, but large particles can not inhibit the recrystallization. At low or high Z values, dynamic recrystallization may occur be- fore dynamic precipitation and proceeds faster. In both cases, secondary phase precipitation is observed along prior austenite grain bounda- ries. Stress relaxation tests at the same deformation temperatures also confirm the possibility of dynamic precipitation. Unexpectedly, the Avrami＇s exponent value increases with the increase of Z value. It is associated with the priority of dynamic recrystallization to dynamic precipitation at higher Z values.

乙酸功能化离子液体作为高效、可回收的催化剂用于2-萘酚与芳醛缩合反应(英文)

An efficient solvent‐free protocol for the synthesis of 14‐aryl‐14H‐dibenzo[a,j]xanthenes from the condensation of 2‐naphthol with arylaldehydes, using acetic acid functionalized imidazolium salts (1‐carboxymethyl‐3‐methylimidazolium bromide ([cmmim]Br) and 1‐carboxymethy1‐3-me-thylimidazolium tetrafluoroborate([cmmim]BF4) as reusable catalysts, has been developed. The turn over frequency on the catalysts is several times higher than the other previously reported catalysts. Also, thermal gravimetric analysis and powder X‐ray diffraction pattern of the catalysts have been studied.

Geomorphological Structures of Jashak Salt Dome

Salt domes have always been attractive because of special attribute due to chemical and physical properties of salt.Jashak salt dome is one of Hormoz series domes,which is appeared in the southeast part of Zagros Mountains and has a great potential for being a geotourism zone in that region as a result of amazing geomorphological structures which made it

Trichoderma species collected from Iran

In order to identify Trichoderma species isolated from Iran, Trichoderma selective media and malt extract agar (MEA) were used to isolate Trichoderma species from the soil samples. All the cultures were purified on 2% water agar by hyphal tip method prior to morphological examination. Morphological observations were carried out on the cultures grown on 2% MEA and oat meal agar at 20°C under ambient laboratory conditions. Macroscopic features of colony and microscopic features of conidiophore, phialid and conidium including position of phialids on conidiophore and shape and size of phialids and conidia were studied and recorded 3-5 days after inoculation. Out of 36 tested isolates, using morphological features and molecular data obtained from ITS1, ITS2 and 5.8S regions fourteen species were identified as follow: T. atroviride, T. ghanense, T. spirale, T. erinaceum, T. citrinoviride, T. saturnisporum, T. longibrachiatum, T. hamatum, T. harzianum, T. inhamatum, T. tomentosum, T. virens, T. asperellum, T. koningii. Among the species T. harzianum and T. virens isolates were the most frequent species. In addition of the mentioned species two Tichoderma sp. were collected from walnut rhizospher that they are not fit to any described species so far. Although one of them are T. brevicumpactum introduced informally.

Effects of Heat Treatment on Microhardness of Some Al-Cu Alloy Prepared by Vacuum Coating

In this paper binary alloy of Al-Cu with composition Al(100-x)Cux, (x = 10, 15, 20) is prepared by thermal evaporation method. The prepared samples are annealed at different temperatures and investigated by XRD and microhardness method. XRD has been used to show amorphous state of structures and microhrdness tester show the increase in hardness due to the increase in amount of Al in the alloy. SEM and AFM were also used to show information about the surface of the specimen, resulting some densification and relaxation in these specimens.

Estimating Water Retention with Pedotransfer Functions Using Multi-Objective Group Method of Data Handling and ANNs

Pedotransfer functions(PTFs) have been developed to estimate soil water retention curves(SWRC) by various techniques.In this study PTFs were developed to estimate the parameters(θ s,θ r,α and λ) of the Brooks and Corey model from a data set of 148 samples.Particle and aggregate size distribution fractal parameters(PSDFPs and ASDFPs,respectively) were computed from three fractal models for either particle or aggregate size distribution.The most effective model in each group was determined by sensitivity analysis.Along with the other variables,the selected fractal parameters were employed to estimate SWRC using multi-objective group method of data handling(mGMDH) and different topologies of artificial neural networks(ANNs).The architecture of ANNs for parametric PTFs was different regarding the type of ANN,output layer transfer functions and the number of hidden neurons.Each parameter was estimated using four PTFs by the hierarchical entering of input variables in the PTFs.The inclusion of PSDFPs in the list of inputs improved the accuracy and reliability of parametric PTFs with the exception of θ s.The textural fraction variables in PTF1 for the estimation of α were replaced with PSDFPs in PTF3.The use of ASDFPs as inputs significantly improved α estimates in the model.This result highlights the importance of ASDFPs in developing parametric PTFs.The mGMDH technique performed significantly better than ANNs in most PTFs.

Silica-supported 1,3-dichloro-5,5-dimethylhydantoin(DCH) as a useful reagent for microwave-assisted aromatization of 1,3,5-trisubstituted pyrazolines under solvent-free conditions

1,3,5-Trisubstituted pyrazolines are rapidly and conveniently oxidized to their corresponding pyrazoles by 1,3-dichloro-5,5- dimethylhydantoin（DCH） in solution and solvent-free conditions under microwave irradiation.The presence of silica gel as a supporting agent is shown to be effective in reducing the reaction times and increasing the yields.

Thymus vulgaris L.,Glycyrrhiza glabra or Combo^(®)enzyme in corn vs.barley-based broiler diets

Objective:To test the effect of supplementation of Thymus vulgaris L.(T.vulgaris)or Glycyrrhizaglabra(G.glabra)in corn-soybean meal diets as well as the inclusion of an exogenous enzyme i.e.Combo^(®)in barley-soybean meal diets together with mentioned medicinal plants in broiler diets.Methods:A total of 270 unsexed 1-day-old broiler chickens(Ross 308)was randomly assigned to 6 treatments with 3 replications of 15 birds in each.Diets were comprised of the control(T1),the inclusion of T.vulgaris,G.glabra,their mixture(equal amount),Combo^(®)supplementation(T2,T3,T4 and T5,respectively)in diets based on corn-soybean meal diets and enzyme supplementation plus equal amount of tested medicinal plants(T6)based on barley-soybean meal diets.Medicinal plants and enzyme were included in diets at level 0.5%and 0.2%of diets,respectively.Results:The highest feed intake was obtained by T1 at 1-21 d of age(P<0.05).All diets caused significant increases in weight gain and significant decreases in feed conversion ratio compared to control at this age(P<0.05).Significant reductions were acquired in feed intake by T3 and T6 at 22-42 d of age(P<0.05).All diets significantly decreased total number of aerobic bacteria,coliforms,Gram-negative bacteria and increased lactic acid bacteria compared to control(P<0.05).Conclusions:The results showed that basal diet has vital character to effectiveness of medicinal plants in broiler diets.Beneficial effects on intestinal microflora were brought by use of T.vulgaris L.and G.glabra in corn-based diets or in barley-based diets together with enzyme.Thus,this capability can support growth performance of broiler chickens at lower age.