scholarly journals Effects of Isothermal Temperature and Soaking Time on Water Quenched Microstructure of Nickel-Based Superalloy GH3536 Semi-Solid Billets

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4668
Author(s):  
Guanfei Xiao ◽  
Jufu Jiang ◽  
Ying Wang ◽  
Yingze Liu ◽  
Ying Zhang ◽  
...  
Keyword(s):  
Ostwald Ripening ◽  
Early Stage ◽  
Solid Particles ◽  
Isothermal Treatment ◽  
Soaking Time ◽  
Nickel Based Superalloy ◽  
Irregular Shapes ◽  
Liquid Phases ◽  
Semi Solid ◽  
Ostwald Ripening Mechanism

Semi-solid billets of GH3536 alloy were prepared by semi-solid isothermal treatment of wrought superalloy method. GH3536 samples were soaked at several semi-solid temperatures (1350 °C, 1360 °C, 1364 °C, and 1367 °C) for 5–120 min. The effects of temperature and soaking time on the microstructure of GH3536 billets were studied. The results indicated that the microstructure was affected by coalescence mechanism, Ostwald ripening mechanism, and breaking up mechanism. Semi-solid microstructure of GH3536 alloy was composed of spherical solid particles and liquid phases, and the liquid phases affected the microstructure greatly. At 1350 °C, the coalescence mechanism was dominant at the early stage of isothermal treatment, then the Ostwald ripening mechanism played a major role for the longer soaking times. At higher temperatures, the breaking up mechanism occurred to form large irregular grains and small spherical grains. As the heating continued, the Ostwald ripening mechanism was dominant. However, at 1364 °C and 1367 °C, the solid grains had irregular shapes and large sizes when the isothermal time was 120 min. The optimum parameters for the preparation of GH3536 semi-solid billets were: temperature of 1364–1367 °C and soaking time of 60–90 min.

Short-Term Oxidation Behavior, Microstructure Evolution and Compression Behavior of Nickel-Based Superalloy GH4037 in Solid and Semi-Solid States

2022 ◽  
Vol 327 ◽  
pp. 11-25
Author(s):  
Guan Fei Xiao ◽  
Ju Fu Jiang ◽  
Ying Wang ◽  
Ying Zhe Liu ◽  
Ying Zhang ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Deformation Mechanism ◽  
Deformation Zone ◽  
Solid Particles ◽  
Isothermal Treatment ◽  
Short Term ◽  
Solid States ◽  
Nickel Based Superalloy ◽  
Semi Solid ◽  
Solid Temperature

Semi-solid processing combines the advantages of traditional forging and casting methods, so it has received much attention recently. However, the research on semi-solid behaviors of Nickel-based superalloys has been rarely reported. In order to investigate the behaviors of Nickel-based superalloy at solid and semi-solid states, oxidation experiments, isothermal treatment experiments and deformation experiments of GH4037 alloy were studied. Short-term oxidation experiments of GH4037 alloy were carried out at a solid temperature (1200 °C) and a semi-solid temperature (1360 °C). The results indicated that the oxides formed at 1200 °C were mainly composed of TiO2, Cr2O3 and a small amount of spinels NiCr2O4, while the oxides formed at 1360 °C consisted of the spinels of NiCr2O4, NiWO4 and NiMoO4 besides TiO2 and Cr2O3. Microstructure evolution of GH4037 alloy after semi-solid isothermal treatment at 1370 °C and 1380 °C was studied. The results indicated that semi-solid microstructures consisted of equiaxed solid grains and liquid phases. The average grains size and shape factor of solid grains were affected by melting mechanism and grain growth mechanism. Compression behaviors of GH4037 alloy after compressed at 1200 °C and 1360 °C were investigated. The results indicated that the flow stress of 1360 °C decreased significantly compared to that of 1200 °C. The deformation zones in the specimens were divided into three parts: the difficult deformation zone, the large deformation zone, and the free deformation zone. At 1200 °C, the deformation mechanism was plastic deformation mechanism. At 1360 °C, sliding between solid particles (SS), liquid flow (LF), flow of liquid incorporating solid particles (FLS), plastic deformation of solid particles (PDS) coexisted in the compression specimen.

Comparison of Semisolid Microstructure Evolution of Wrought Nickel Based Superalloy GH4037 with Different Solid Fraction

2019 ◽  
Vol 285 ◽  
pp. 105-110
Author(s):  
Guan Fei Xiao ◽  
Ju Fu Jiang ◽  
Ying Wang ◽  
Ying Zhe Liu
Keyword(s):  
Solid Fraction ◽  
Microstructure Evolution ◽  
Isothermal Treatment ◽  
Liquid Droplets ◽  
Soaking Time ◽  
Isothermal Temperature ◽  
Nickel Based Superalloy ◽  
Temperature Ranges ◽  
Semi Solid ◽  
Average Size

The research on semisolid metal forming of Ni-based superalloys is limited because of the difficulties in preparing semisolid billets. Traditional methods for fabricating semisolid billets are SIMA and RAP. In order to decrease the processing procedures, a new method called semi-solid isothermal treatment of wrought superalloy (SSITWS) was used to fabricate semisolid billets in this paper. In order to get the optimal parameters to fabricate Ni-based GH4037 semisolid billets, the effects of isothermal temperature and soaking time on microstructure evolution were investigated. The isothermal temperature ranges from solidus to liquidus, and the soaking time ranges from 10min to 60min. The results show that near-globular grains can be obtained only in the semi-solid state with appropriate solid fractions. When the solid fraction was high, the shape of grains was irregular and the average size of grains was large and inhomogeneous. When the isothermal temperature reached 1350°C, spherical grains appeared, and many small intragranular liquid droplets existed. During the appropriate isothermal temperature range, from 1350°C to 1380°C, the shape of solid grains was globular and the size of solid grains was homogeneous. At the same time, the size of the grains and the roundness of the grains increased with the increasing of isothermal temperature.

Effect of isothermal process parameters on semi-solid microstructure of chip-based Al–Cu–Mn–Ti alloy prepared by SIMA method

2020 ◽  
Vol 34 (33) ◽  
pp. 2050385
Author(s):  
Ye Wang ◽  
Maoliang Hu ◽  
Hongyu Xu ◽  
Zesheng Ji ◽  
Xuefeng Wen ◽  
...  
Keyword(s):  
Process Parameters ◽  
Ostwald Ripening ◽  
Isothermal Holding ◽  
Treatment Temperature ◽  
Holding Time ◽  
Isothermal Treatment ◽  
Isothermal Process ◽  
Semi Solid ◽  
Average Size ◽  
Relationship Of

A typical Al–Cu–Mn–Ti aluminum alloy chip was adopted to prepare semi-solid billets by a Strain-Induced Melt Activation (SIMA) method, and the effects of isothermal process parameters on the semi-solid microstructure evolution of the alloy were investigated in this work. The result showed that semi-solid billets with highly spheroidal and homogeneous fine grains could be prepared from chips by the SIMA method. With the increase of isothermal temperature, the finer and near-spherical grains are obtained, the grains coarsen and became ellipse at 903 K because of the coarsening mechanisms of coalescence and Ostwald ripening. The relationship of isothermal holding time and grains size followed the LSW theory well, and more spherical microstructure can be brought by prolonging the holding time until 3000 s. Thus, the optimal isothermal treatment temperature is 893 K and holding time is 3000 s, the corresponding average size and roundness of grains are 137 [Formula: see text]m and 1.108, respectively.

Kinetics of Coarsening and Solid Sphericity during Reheating of Ductile Iron and Al Alloys

2006 ◽  
Vol 116-117 ◽  
pp. 205-208 ◽  
Author(s):  
P. Babaghorbani ◽  
S. Salarfar ◽  
Mahmoud Nili-Ahmadabadi
Keyword(s):  
Cast Iron ◽  
Solid State ◽  
Ostwald Ripening ◽  
Ductile Cast Iron ◽  
Al Alloys ◽  
Solid Particles ◽  
Coarsening Kinetics ◽  
Semi Solid ◽  
Reheating Process ◽  
Kinetics Of

Reheating process in the semi-solid state is a very important step in the thixoforming process. In this research semi-solid ductile cast iron and Al alloys (Al-2.5Si, Al356) prepared by inclined plate method, were reheated to examine the effect of reheating conditions on the microstructure and coarsening kinetics of the alloys. For ductile cast iron, solid fraction at different reheating temperatures and holding times was obtained and based on these results the optimum reheating temperature range was determined. In the case of Al alloys increase of holding time in the semi-solid state, leads to increase of liquid fraction, solid grain size and improvement of sphericity of solid particles. In addition, the results show that coarsening kinetics of microstructures of both alloys during reheating was diffusion controlled and can be mostly treated by Ostwald ripening theory.

Microstructural Evolution of ZL104 Aluminum Alloy Semi-Solid Billet Fabricated by RAP Process

2019 ◽  
Vol 285 ◽  
pp. 234-239
Author(s):  
Yong Fei Wang ◽  
Sheng Dun Zhao ◽  
Chao Chen ◽  
Peng Dong ◽  
Peng Zhang
Keyword(s):  
Aluminum Alloy ◽  
Ostwald Ripening ◽  
Isothermal Holding ◽  
Isothermal Treatment ◽  
Liquid Droplets ◽  
Microstructural Coarsening ◽  
Average Grain Size ◽  
Cold Rolled ◽  
Semi Solid ◽  
Holding Temperature

In this study, ZL104 aluminum alloy supplied in cold rolled state was introduced in recrystallization and partial melting (RAP) process to fabricate semi-solid billets. During the RAP process, samples cut from cold rolled ZL104 aluminum plate were heated to different semi-solid temperatures, and the effects of isothermal treatment parameters on the microstructures of semi-solid billets were investigated. Results showed that, with the increase of isothermal holding temperature and time, both the average grain size and the shape factor were increased. Namely, the shape of solid grain was more and more spherical, but the size of solid grain was larger and larger, which may be not suitable for semi-solid forming. The size of liquid droplets was increased while the number of liquid droplets was decreased with increasing the isothermal holding temperature and time. Microstructural coarsening of solid grain were attributed to coalescence and Ostwald ripening mechanisms, however, the latter one played a more and more important role with the increase of isothermal holding time and temperature. Additionally, The optimal isothermal holding temperature and time are 570 °C and 5 min, respectively, and the coarsening rate constant is 1357.2 μm3/s at 570 °C.

scholarly journals Effect of Y Addition on the Semi-Solid Microstructure Evolution and the Coarsening Kinetics of SIMA AZ80 Magnesium Alloy

2017 ◽  
Author(s):  
Qi Tang ◽  
Hao Sun ◽  
Mingyang Zhou ◽  
Gaofeng Quan
Keyword(s):  
Magnesium Alloy ◽  
Microstructure Evolution ◽  
Shape Factor ◽  
Ostwald Ripening ◽  
Optical Microscope ◽  
Isothermal Treatment ◽  
Az80 Magnesium Alloy ◽  
Coarsening Kinetics ◽  
Semi Solid ◽  
Az80 Alloy

Semi-solid feedstock of AZ80 magnesium alloy modified by minor rare-earth Y element (0, 0.2, 0.4, 0.8 wt.%) were fabricated by strain induces melting activated (SIMA) in the form of extrusion and partial remelting. The effect of Y addition on the microstructure evolution of extruded and isothermal treated alloy was observed by optical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD) and quantitative analysis. The results show that the Y addition can refine the microstructure and make the β-Mg17Al12 phases agglomerating. During the subsequent isothermal treatment at 570℃, the average solid grain size, shape factor and liquid fractions increased with prolonged soaking time. Smaller spheroidal solid grains and the larger shape factor were obtained due to Y addition. The coalescence and Ostwald ripening of solid grains operated the coarsening process simultaneously. The coarsening rate constants of AZ80M1 (0.2 wt.% Y addition) of 164.22 μm3s-1 was approximately four times less than the un-modified AZ80 alloy of 689.44 μm3s-1. In contrast, the desirable semi-solid structure featured by fine, well globular solid grains and appropriate liquid fractions and shape factor was achieved in AZ80M1 alloy treated at 570℃ for 20-30 min.

Phase Separation: From the Initial Nucleation Stage to the Final Ostwald Ripening Regime

1997 ◽  
Vol 481 ◽  
Author(s):  
Celeste Sagui ◽  
Dean Stinson O'Gorman ◽  
Martin Grant
Keyword(s):  
Phase Separation ◽  
Late Stage ◽  
Ostwald Ripening ◽  
Early Stage ◽  
Classical Problem ◽  
Nucleation And Growth ◽  
New Model ◽  
Nucleation Stage ◽  
Initial Nucleation

ABSTRACTIn this work we have re-examined the classical problem of nucleation and growth. A new model considers the correlations among droplets and naturally incorporates the crossover from the early-stage, nucleation dominated regime to the scaling, late-stage, coarsening regime within a single framework.

Formation Mechanism of Thixotropic Microstructure of AM60 Alloy during Solidification

2014 ◽  
Vol 1030-1032 ◽  
pp. 86-89
Author(s):  
Bo Xing
Keyword(s):  
Formation Mechanism ◽  
Solid Substrate ◽  
Research Field ◽  
Primary Phase ◽  
Solid Particles ◽  
Metallographic Analysis ◽  
Semisolid Slurry ◽  
Dendritic Microstructure ◽  
Quenching Method ◽  
Semi Solid

A research field on semi-solid metal processing is the preparation of semi-solid slurry with non-dendritic microstructure. Nowadays, with the technological innovation of semi-solid slurry preparation, people turn to produce the non-dendritic semisolid microstructure by locally cooling of the alloy melt during solidification. Therefore, it is necessary to investigate the formation mechanism of the non-dendritic microstructure formation because the primary phase undergoes a specially controlled nucleation and growth which distinctly different from the commom solidification. In this paper, the semisolid slurry of AM60 alloy was produced by Self-Inoculation Method (SIM), and the microstructure evolution of primary α-Mg was investigated by water quenching method and metallographic analysis. The results indicate that the semisolid microstructure of AM60 alloy produced by SIM composed of small and globular α-Mg particles, and these grains undergone a coarsing process during quiescent holding. The solid substrate caused by the fusion of solid particles and the dendritic fragments caused by melt flow caused the grain multiplication, and then the grain undergone a steadily growth because of the uniform temperature distribution, resulting in the increase of grains density and a small grain size of the AM60 semisolid slurry.

scholarly journals Effect of Mg Treatment on the Nucleation and Ostwald Growth of Inclusions in Fe-O-Al-Mg Melt

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3355
Author(s):  
Yutang Li ◽  
Linzhu Wang ◽  
Chaoyi Chen ◽  
Junqi Li ◽  
Xiang Li
Keyword(s):  
Nucleation Rate ◽  
Ostwald Ripening ◽  
Critical Size ◽  
Early Stage ◽  
Inclusion Size ◽  
Nucleation Theory ◽  
Mg Addition ◽  
Homogeneous Nucleation Theory ◽  
Mg Melt ◽  
Size Of Nuclei

This study aimed to investigate the effect of Mg treatment on the nucleation and ostwald growth of inclusions. Deoxidized experiments with Al (0.05%Al) and Al-Mg (0.05%Al + 0.03%Mg) were carried out at 1873 K, and the composition, number, and size of inclusions were studied as a function of holding time. Homogeneous nucleation theory and ostwald ripening were utilized to calculate the nucleation rate, the critical size of nuclei, and coarsening rate of inclusions. The results show that small inclusions were more easily found in the steels with Al-Mg complex deoxidation, and the number of inclusions with Al-Mg complex deoxidation is larger at an early stage of deoxidation. The critical size of nuclei increases in the order of MgAl2O4 (0.3–0.4 nm) < Al2O3 (0.4–0.6 nm), and the nucleation rate increases in the order of Al2O3 (1100 cm−3 s−1) < MgAl2O4 (1200 cm−3s−1), which is consistent with the experimental results. Moreover, the coarsening rate of MgAl2O4 inclusions was smaller than Al2O3 inclusions in both the value of kd(cal.) from ostwald growth and the value of kd(obs.) from inclusion size. The effect of Mg addition on coarsening of inclusion was analyzed and their mechanism was discussed based on ostwald ripening theory and Factsage calculation.

scholarly journals Development of cyclosporine-loaded nanoemulsion for topical treatment of psoriasis

2019 ◽  
Vol 10 (SPL1) ◽  
Author(s):  
Siti Hajar Musa ◽  
Norazlinaliza Salim ◽  
Norashikin Shamsudin ◽  
Mahiran Basri ◽  
Hamid Reza Fard Masoumi
Keyword(s):  
Topical Treatment ◽  
Oral Delivery ◽  
Ostwald Ripening ◽  
Normal Skin ◽  
Severe Case ◽  
Transepidermal Water Loss ◽  
Water Soluble ◽  
Colloidal System ◽  
Thaw Cycle ◽  
Ostwald Ripening Mechanism

Psoriasis is an autoimmune disease in which the symptoms are obviously appeared on the patient's body with thick, red/ salmon colour and dry patches. Clinically, topical treatment has been the first-line treatment for psoriasis, whether or not the systemic and phototherapy is required. Currently, cyclosporine is one of the standard oral medications used for moderate to a severe case of psoriasis. However, through oral delivery, it cannot be used for a long period and causes bad effects. Thus, a new delivery system of cyclosporine is in need to be developed to overcome its toxic effects by skipping the first pass body metabolism. A nanoemulsion colloidal system, as the main carrier for big, non-water-soluble cyclosporine, is believed could help in the delivery of activities through the stratum corneum of the skin layer. Nanoemulsion system, which mainly consists of oil phase (a mixture of virgin coconut oil, nutmeg oil, and cyclosporine), aqueous phase, and surfactant, was successfully being developed by using Mixture Experimental Design optimization tool with droplet size range between 110-160 nm. Stability studies were carried out with respect to; pH, storage at different temperatures, coalescence and Ostwald ripening mechanism, free-thaw cycle, and FTIR analysis. From the obtained results, this newly-developed nanoemulsion containing cyclosporine was proven to be stable and successfully maintained its physicochemical characteristics even after 3 months of storage at 4°C and 25°C temperature. Ostwald ripening mechanism contributed to the instability of the system at 45°C of storage. Introduction of standard cyclosporine, blank nanoemulsion, and nanoemulsion containing cyclosporine to the HaCaT cells in the treatment of MTT assay study has confirmed the safety of the nanoemulsion. Permeation study of the newly-developed nanoemulsion containing cyclosporine showed it was best fitted the Korsmeyer-Peppas kinetic model. In addition, the transepidermal water loss and hydration studies proved the efficacy of cyclosporine-loaded nanoemulsion in increasing the water storage of the volunteers’ normal skin after 3h of application.  

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