Secondary Dendrite Arm Research Articles

Prediction of the influence of welding metal composition on solidification cracking of laser welded aluminum alloy

The crack length of laser welding 6082 aluminum alloy with three types of 5000 series aluminum alloy welding materials was compared by fishbone test method. It was found that ER5A06 welding material corresponds to the shortest crack length, indicating that the welding material composition has an impact on the welding crack and the crack susceptibility could be controlled by adjusting the welding material composition. Combined with SEM and EBSD, the crack morphology was observed and determined to be solidification cracking. Through EDS, EPMA and thermodynamic calculation, it is found that the main elements affecting solidification cracking are Al, Mg, Si and Cu. The cooling rate of the fusion zone was calculated according to the secondary dendrite arm spacing and welding composition. Compared with casting and arc welding, the laser welding aluminum alloy fusion zone has rapid cooling rate. Due to the rapid cooling rate, the T-fs curves of Al-Mg, Al-Si and Al-Cu binary alloys were calculated by commercial thermodynamic software Thermo-Calc. Furthermore, the cracking susceptibility index (CSI) of binary aluminum alloys were also calculated to determine the element content range of the cracking. To understand the element interaction, both the machine learning and computational thermodynamic methods were employed to predict the influence of multi-component welding metal on solidification cracking susceptibility. Based on the calculation results of solidification cracking susceptibility for binary aluminum alloys, a data set containing 45 groups of aluminum alloy components was established and set as the input dataset. The CSI values corresponding to the compositions in the data set were set as the target and the relationship “welding metal composition - CSI” was founded. Based on the Kriging model, the influence of welding metal composition on solidification cracking susceptibility and the components of most crack susceptible were obtained, which provides a basis for welding materials design.

Effects of Cu/Er on Tensile Properties of Cast Al-Si Alloy at Low Temperature.

The current protocol presents the effects of the addition of Cu, rare earth Er, and Cu-Er composite elements on the microstructure of the Al-10Si-0.3Mg alloy. The variations in their low-temperature tensile properties were also investigated. The addition of rare earth Er elements, Cu elements, and Cu-Er composite elements increased the strength of all three groups of alloys when stretched at low temperatures (-60 °C). Further, the elongation of the alloy increased with the addition of Er, while the elongation of the other two groups decreased. The low-temperature (-60 °C) tensile strength of the alloy with the same composition was higher than that at room temperature (20 °C), but the elongation decreased. Notably, by adding rare earth Er to the Al-10Si-0.3Mg alloy, the three-dimensional morphology was changed from coarse dendritic to fine fibrous, the secondary dendritic arm spacing (SDAS) of the alloy was reduced, and the grains were refined. The Al2Cu phase, Al-Si-Cu-Mg quaternary phase, and Cu-rich phase appeared in the alloy with the addition of Cu elements, but the Si phase morphology and α-Al dendrites were not significantly improved. Interestingly, the Si phase morphology of the alloy was improved by adding Cu-Er composite elements, and SDAS was reduced. Still, the Al2Cu phase, Al-Si-Cu-Mg quaternary phase, and Cu-rich phase were not much improved.

Multiphase numerical modeling and investigation of heat transfer for quenching of spherical particles in liquid pool

Quenching is a widely applied heat treatment process for metallic materials in order to adjust the microstructure and material properties by means of intensive cooling. Depending on the cooling rate attained with respect to the operating conditions as well as the cooling medium, specific material properties such as hardness can be adapted to engineering applications. One of the major constraints for intensive cooling remains with the selection of suitable process parameters. An imprudent selection will end up with sample distortion and cracks. The process being highly complex involving solidification, liquid pool immersion phenomena, rotation, the Leidenfrost effect and vapor formation emerging from liquid for these “millimeter” ranged particles, which make the complete process difficult to analyze by experimental investigations alone. In order to tackle this challenge, a multiphase numerical modeling based on a Eulerian framework is developed and experimentally validated in this work for analyzing the cooling rate of high temperature semi-solid spheres quenched in water. This model simulates particle quenching in liquids, where the source and sink terms of the conservation equations are modified to accommodate the phase transfer effects. To validate modeling results, a high temperature molten metal droplet generator is used to generate the droplets from Al 4.5-wt.% Cu with a diameter of about 1 mm which are quenched in water during the semi-solid state. The formation of dendritic structure within the solidifying droplet is highly sensitive to its cooling rate. This allows to calculate the cooling rate corresponding to the operating condition from SDAS (Secondary Dendrite Arm Spacing) and compare with numerical simulation. Finally, we investigate the influence of the particle Reynolds number (flow velocity) and pool temperature on heat transfer with this validated model.

Effect of local microstructure on fatigue and related failure mechanisms in AlSi-castings

Mobility applications often demand shape-optimized designs. Casting of AlSi-alloys is an efficient bulk production technology featuring parts with strongly varying wall thickness. The local cooling rate is process controlled, implying severe changes in mechanical properties such as degree of porosity and secondary dendrite arm spacing.This study provides a brief overview about the effect of local microstructural properties, and intrinsic defect distribution, on associated fatigue strength for alloy EN AC 42100 and alloy 46200. Results from extensive fractographic investigations and computed tomography revealed microporosity as the primary failure mechanism for high-cycle-fatigue design, but dependent on the load level and casting process condition other crack initiating imperfections such as oxide films, slip planes and inclusions get more pronounced. A statistical assessment of fatigue strength considered the local manufacturing conditions and the associated varying failure mechanisms.

Effect of Cu Addition on Solidification Microstructure in High Carbon High Speed Steel Type Cast Alloy

Effect of copper addition on solidification microstructure was investigated for high carbon high speed steel type alloys (Fe-2.0%C-5%Cr-5%Mo-5%V-0~4%Cu). The microstructure of all as-cast specimens with different copper content was composed of dendrite of primary γ, MC-γ eutectic and M2C-γ eutectic but it was found X-ray diffraction peaks of α phase by X-ray diffractometry. The volume fraction of each phase in solidification microstructure was approximately constant regardless of copper content. The shapes of dendrite of primary γ changed significantly in response to amount of copper addition: that of specimen with no copper was equiaxed while that of specimen containing copper was columnar which tends to be marked with increasing amount of copper addition. Furthermore, the secondary dendrite arm spacing λ2 decreased with increasing amount of copper addition. As a result, it concluded that the effect of copper addition on solidification microstructure is columnar crystallization and decreasing λ2 of the dendrite with primary γ.

Effect of cooling rate on morphology and distribution of Fe phase in solidification structure of Cu-20Fe alloy

Cu–Fe alloys are high-strength and high-conductivity copper-based materials with great potential. The solidified structures comprise of an Fe phase and Cu matrix, and the solidification structure significantly affects the properties of the alloys. The cooling rate during solidification affects the Fe phase morphologies, sizes, and distribution uniformity in Cu–Fe alloys, making it an essential control parameter. The solidification process of a Cu-20Fe alloy were analyzed at cooling rates from 0.3–13.0 °C/s using a confocal scanning laser microscope (CLSM). The secondary dendrite arm spacing (SDAS) and fractal dimension (D) were used to quantitatively characterize the solidification morphology. The uniformity (U) was used to describe the distribution uniformity of the Fe phase in the solidification structure. The results indicate that the morphology and distribution uniformity of the Fe phase were significantly affected by the cooling rate. The relationship between SDAS (λ2) and cooling rate (C) gave the expression: λ2 = 12.05 · C−0.39. The cooling rate during solidification changed the morphology of the dendrites and the overall solidification structure, likely because of the solute diffusion and temperature gradient in front of the solid–liquid interface being affected. In addition, the distribution uniformity of the Fe phase in the solidification structure significantly changed with the solidification time. There was a linear relationship between uniformity and SDAS: U = 82.50−1.03 × λ2. The morphology and distribution uniformity of the Fe phase in the solidification structure of Cu-Fe alloys can be controlled by adjusting the cooling conditions during solidification. This could allow for the enhancement of the functional properties of the alloy and possibly lead to further applications.

The cooling rate effects on the Nb-B inoculant potential of refining grains and dendritic scale in 6201 alloy

Nb-B refiners are thought to be more stable than Ti-based refiners, becoming promising inoculants for Al alloys. However, the combined effect of adding NbB on dendritic scale and grain size (GS) with a wide range of solidification cooling rates remains unknown. It is well known that the shape of the α-Al phase is determined by a balance between inoculating components content/type and cooling rate. The inoculation of Al alloys with Ti-based inoculants, for example, significantly lowers GS while having no significant effect on secondary dendritic arm spacing (SDAS). Increased cooling rate, on the other hand, results in grain refinement, but only to a limited extent. Because of a combination of appropriate mechanical properties and suitable electrical conductivity, the 6201 alloy is widely employed in the transmission and distribution of electricity. Despite being a thermomechanically treated alloy, it goes through a melting and solidification process first, which entail research on this level of processing. ln order to assess the impact of adding NbB to the 6201 alloy’s refinement level (either macro or microscopic), directional solidification (DS) and centrifugal casting (CC) processes were utilized to obtain samples for examination. For the DS samples, cooling rates were determined, whereas for the CC samples, they were approximated for two alloys: 6201 (reference) and 6201-0.5wt.%Nb-0.1wt.%B alloys. Comparing the refined and non-refined alloy results, the GS of the DS 6201-NbB alloy was much smaller (about 13 times) across a range of cooling rates from 0.5 K/s to 20 K/s, whereas only 3 times smaller GS values were detected for CC samples at higher cooling rates. For particular cooling rates of 2.5 K/s and 240 K/s, the GS/SDAS ratios of values related to slow and fast cooling were 6.9 and 6.2, demonstrating that the cooling rate sensitivity of both GS and SDAS was similar in the NbB-inoculated alloy.

Quantitative assessment of inhomogeneity of dendritic structure of aluminum alloys based on their microstructural analysis

The microstructure of various aluminum alloys is studied by measuring the secondary dendrite arm spacings. To process the experimental data, the mathematical apparatus of the lognormal distribution is used. It is shown that this approach provides an effective convolution of experimental information for the calculation estimate of the mesoscale inhomogeneity of secondary dendrite arm spacing.

Characterization and modeling of damage behavior of a casting aluminum wheel considering inhomogeneity of microstructure and microdefects

For a meaningful description of casting processes on component behavior, the inhomogeneities of the microstructure, microdefects, and mechanical properties including damage behavior in a casting aluminum wheel were experimentally characterized. Both effects of microstructure/microdefects and stress state on damage behavior were determined by performing smooth and notched tensile tests and torsion tests on specimens extracted from different positions. The distribution of microstructure and microdefects in the cast wheel and the corresponding effects on damage development were analyzed using metallography, 3D X-ray CT, and SEM. Casting simulations were performed to determine distributions of local parameters like solidification time, secondary dendrite arm spacing (SDAS), and porosity. It is clear that the ultimate strength and elongation decrease with increasing porosity and SDAS. A material model describing the influence of porosity on flow stress and a damage model describing the relationships of fracture strain with porosity and triaxiality were developed based on the experimental and numerical results. The correlations of yield stress and elongation with porosity were applied to calibrate the models. Additionally, the influence of stress triaxiality on fracture strain was determined using torsion and notched tensile tests for selected porosities and the corresponding inverse simulations. Simulations of the different specimen tests with the developed material model and damage model could satisfactorily describe the experimental results. This method builds a good basis for coupling between casting simulation and structural simulation to optimize manufacturing processes and develop lightweight products. Improving the precision of microdefect calculation in casting simulations and applying of a stochastic model in structural simulations are important future works.

Effects of cooling rates on the solidification behavior, microstructural evolution and mechanical properties of Al–Zn–Mg–Cu alloys

The effects of different cooling rates (0.3–66.2 K/s) on the solidification behavior, microstructural evolution, and mechanical properties of Al–Zn–Mg–Cu alloys during a short-flow process were investigated in detail. With the increasing cooling rate, the grain size first increased, then decreased, and finally, again increased, whereas the secondary dendrite arm spacing and the crystalline phase size were greatly reduced. Relatively high cooling rates (3.4–66.2 K/s) significantly increased elemental micro-segregation in α-Al due to the transition of the solidification mode from near-equilibrium to the Scheil mode. Moreover, the element trapping capacity at the end of solidification was enhanced at high cooling rates, especially for alloy D (66.2 K/s). Hence, the crystalline phase content first increased and then decreased at high cooling rates. During the short-flow process, the refinement of the crystalline phase and dendrites significantly promoted the re-dissolution of the crystalline phase and the elemental diffusion process, leading to improved mechanical properties. The yield strength, the tensile strength, and the elongation were improved from 420 MPa, 460 MPa, and 4.5% for alloy A to 457 MPa, 524 MPa, and 11.3% for alloy D, respectively.

Size-dependent microstructure evolution and formation mechanisms during the gas atomization process of FGH4113A Ni-based superalloy powder

A novel microstructure evolution mechanism is proposed to optimize the preparation process of superalloy powders. This study focuses on the solidification segregation, as well as the correspondence between the powder sizes and the microstructure evolution mechanism of Ni-based superalloy fine powders. The quantitative analysis was systematically examined using thermodynamic analysis. The results indicated that dendrites and cellular microstructures formed on the surface and interior of the powders, but their key distribution characteristics were highly related to both the powder size and ultra-fine satellite particles that adhered to its surface. The number of ultra-fine satellite particles, outgrowth index, spacing between the secondary dendrite arms increased with the increasing powder size, exhibiting an ideal linear relationship. In particular, when the powder size was small, the length of the internal primary dendrite arms increased as the powder particle size increased, but interestingly, remained at approximately 30 μm when the particle size exceeded 45 μm. Finally, a model for the microstructural evolution mechanism of the surface and interior of alloy powders ≤100 μm was developed, which lays the theoretical foundation for the preparation of superalloy powders.

Comparison of Dynamical and Empirical Simulation Methods of Secondary Dendrite Arm Coarsening

The physical and mechanical properties of an entirely (wrought alloys) or partly (cast alloys) dendritically solidified alloy strongly depend on the secondary dendrite arm spacing (SDAS). The casting practice and the simulation of solidification need a usable but simple method to calculate the SDAS during and at the end of solidification as a function of the cooling rate. Based on many solidification experiments, a simple equation to calculate the SDAS (empirical method) is known to use the local solidification time, which can be obtained from the measured cooling curves (equiaxed solidification), or can be calculated from the temperature gradient and front velocity (directional solidification). This equation is not usable for calculating the SDAS during solidification. Kirkwood developed a semi-empirical method based on the liquid phase’s diffusion, which contains only one geometric factor that seems constant for different alloys. This equation contains some physical parameters that depend on the temperature, so the equation cannot be integral in closed form. In the present work, first, we show the effect of the curvature of the solid/liquid interface on the equilibrium concentrations and then the different processes of SDA coarsening. In our earlier paper, we demonstrated that using the empirical method, the final SDAS can be calculated with acceptable correctness in the case of four unidirectional solidification experiments of Al-7wt%Si alloy. The present work shows that numerically integrated Kirkwood’s equations used the known cooling curve; the SDAS can be calculated at the end and during solidification in good agreement with these experimental results. Compared to the two calculation methods, we stated that the correctness of the methods is similar. Still, the results of the solidification simulation (the microsegregation) will be more correct using the dynamical method. It is also shown that with the dynamical method, the SDAS can be calculated from any type of cooling curve, and using the dynamical method, it is proved that some different SDASs could belong to the same local solidification time.

Quantitative and Qualitative Assessment of As-Cast Microstructure and Microporosity of γ-γ′ Co-based Superalloys

The γ-γ′ Co-based alloys have attracted extensive attention as a new class of materials for high temperature applications. The work is focused on quantitative and qualitative microstructural characterization of selected γ-γ′ type Co-based superalloys obtained by gravity casting. The four Co-based alloys were prepared via vacuum induction melting. The microstructure was analyzed by means of light microscopy and scanning electron microscopy. The microstructural parameters such as porosity and secondary dendrite arm spacing (SDAS) were evaluated by image analysis. The new Co-based superalloys are characterized by proper as-cast microstructure owing to low SDAS and limited microporosity. The values of secondary dendrite arm spacing are comparable for all alloys. The W-free alloys containing Mo and Nb exhibit substantially lower shrinkage porosity compared to those of Co–Al–W and Co–Ni–Al–W. Due to crystallization of Mo and Nb rich phases at lower temperatures, these alloys are characterized by higher solidification range.

Alloy solidification: Assessment and improvement of an easy-to-apply model

• The Gong-Chen model requires no experimental parameters and is easy to apply. • It can be used as a generic solidification model up to the solid fraction (fs) of 0.9. • When fs > 0.9, its applicability depends on both solute diffusion and partition coefficient. • The Gong-Chen model requires f s Lever > 1, which has been examined and justified. • The Won-Thomas model provides the most practical predictions but requires experimental input. It has been a central task of solidification research to predict solute microsegregation. Apart from the Lever rule and the Scheil-Gulliver equation, which concern two extreme cases, a long list of microsegregation models has been proposed. However, the use of these models often requires essential experimental input information, e.g. , the secondary dendrite arm spacing ( λ ), cooling rate ( T ˙ ) or actual solidification range ( Δ T ). This requirement disables these models for alloy solidification with no measured values for λ, T ˙ and Δ T . Furthermore, not all of these required experimental data are easily obtainable. It is therefore highly desirable to have an easy-to-apply predictive model that is independent of experimental input, akin to the Lever rule or Scheil-Gulliver model. Gong, Chen, and co-workers have recently proposed such a model, referred to as the Gong-Chen model, by averaging the solid fractions ( f s ) of the Lever rule and Scheil-Gulliver model as the actual solid fraction. We provide a systematic assessment of this model versus established solidification microsegregation models and address a latent deficiency of the model, i.e., it allows the Lever rule solid fraction f s to be greater than one ( f s > 1). It is shown that the Gong-Chen model can serve as a generic model for alloy solidification until f s reaches about 0.9, beyond which ( f s > 0.9) its applicability is dictated by both the equilibrium solute partition coefficient ( k ) and the solute diffusion coefficient in the solid ( D s ), which has been tabulated in detail.

Effects of solidification rate and heat treatment on microstructure characterization and hot tensile strength of single crystal CMSX-4 superalloy

Single crystal CMSX-4 Ni-based superalloy, consisting of rhenium and hafnium elements, were directionally solidified at three different withdrawal rates of 2, 3, and 4 mm/min through a Bridgman furnace. After that a full solution heat treatment was followed by two step aging at 1140 °C/6 h and 870 °C/20 h respectively. Microstructural characteristics, e.g. the primary and secondary dendrite arm spacing, the size and volume fraction of γ ́ phase, and percentage of porosity were analyzed using the optical microscopy (OM) and scanning electron microscopy (SEM) equipped with an energy dispersive spectroscopy (EDS) detector. It was found that an increase in the withdrawal rate of the as-cast specimens led to a reduction in the values of primary and secondary dendrite arm spacing, the percentage of porosity and also size of γ ́. In addition, at higher withdrawal rates, the γ/γ ́ eutectic phase is distributed from a continuous and blocky shaped to fine scattered islands. Nevertheless, the minimum volume fraction of eutectic was obtained at the withdrawal rate of 3 mm/min. Heat-treatment of the specimens associated with formation of a noticeable cuboidal γ’-precipitates, which was about 70% at withdrawal rate of 3 mm/min. Furthermore, the aged specimens indicated the lower γ/γ ́ eutectic phase compared to as-cast specimens, while the percentage of porosity increased for aged specimens. Eventually, the highest ultimate tensile strength of the single crystal CMSX-4 at 870 °C was measured to be 1170 MPa which was obtained at a withdrawal rate of 3 mm/min, due to the high volume fraction of the γ ́ phase and the lower values of γ/γ ́ eutectic phase.

Quantifying the effects of grain refiners (AlTiB and Y) on microstructure and properties in W319 alloys

For aluminum alloys, grain refinement is the most efficient method to improve both strength and ductility. However, this rule may not apply for the recycled Al due to the large amount of intermetallics. In this paper, both secondary dendritic arm spacing (SDAS) and intermetallics have been quantified as a function of grain refinements including traditional AlTiB and most recent Y refiners. Using U-net CNN machine learning algorithm, both Fe-rich intermetallics and eutectic Si have been successfully segmented from optical and SEM/EDS images. Different from traditional refiners, (AlTiB + Y) not only strengthens the refining ability but also reduces the percentage of harmful needle-like Fe-rich intermetallics and transforms flaky Si particles into fibrous morphology. Harvested from the comprehensive grain refiners, SDAS was reduced by 38.9%, the average equivalent diameter of eutectic Si was reduced by 37.9%, and Fe-rich intermetallics content was significantly reduced. In particular, the microstructure improved by AlTiB+0.05Y (0.6 wt.% AlTiB + 0.3 wt.%Y) resulted in an increase in elongation of the refined alloy to 3.9 ± 0.4%, which is 63.3% higher compared to the base alloy, while the UTS remained at the original 260 MPa. This paper offers a promising refining technology for the recycling and casting of Al-Si alloys. • Hybrid addition of Al-Ti-B and rare earth element Y can achieve improved refining effect. • The morphology of eutectic Si particles and Fe-rich intermetallics can be modified by new grain refiners. • Quantitative information of particle distribution can be obtained by U-net CNN machine learning algorithm • Transforming flaky Si particles into fibrous eutectics and reducing harmful β-Fe size significantly improve the properties. • Combined with thermodynamics, Fe-rich intermetallics reduction mechanism is revealed.

Influence of Alloying Element and Ageing on Microstructure and Dry Sliding Wear Behaviour of Cu-Zn-xNi Alloy

In this paper, we look at how different nickel concentrations (4, 8, and 12 percent) affect the microstructure, microhardness, and dry sliding wear behaviour of a Cu-Zn-xNi alloy. The alloy was created using a casting technique at 1100°C and a heat treatment method that included solution treatment at 600°C and ageing at 450°C for four hours each. Microstructure studies were performed on the developed alloys using a scanning electron microscope (SEM). To investigate alloy indentation resistance, an ASTM E384 microhardness test was performed. Tribological properties such as friction and wear were investigated using a pin on disc tribometer and a dry sliding wear test according to the ASTM G99 standard. SEM studies revealed α-phase (copper) and solid solution of zinc in cast alloys, while aged alloys revealed a similar structure but with the addition of Cu2NiZn precipitates. The microhardness values improved as the Ni content and ageing increased. The decrease in secondary dendrite arm spacing with increasing Ni content and ageing was attributed to the improvement. The coefficient of friction decreased as the load increased, but increased as the sliding velocity increased. However, as loads and sliding velocities increased, so did the wear rate. For the majority of loads and sliding velocities, the worn surface demonstrated abrasion as the dominant wear mechanism.

Effects of Alloying Elements on Solidification Structures and Macrosegregation in Slabs

A Cellular Automaton-Finite Element (CAFE) model and a secondary dendrite arm spacing (SDAS) model are established to study the evolutionary behavior of the macrostructure and the secondary dendrites on a 295 × 2270 mm2 slab cross-section of experimental steel, respectively. The relationship between the element content, SDAS, equiaxed crystal ratio (ECR) and macrosegregation in continuously cast experimental slabs was studied comprehensively. It is found that with the increase in carbon content, the ECR increases at first and then decreases, and the ECR reaches the maximum value when the carbon content is 0.3%. With the increase in carbon content, the SDAS and average grain size of the equiaxed crystal zone increase, whereas the Si and Al content evidently affects the SDAS and average grain size of the equiaxed crystal zone to a greater extent than the Mn content. In addition, the SDAS can be reduced by reducing the content of C and Si within the acceptable range of alloy composition.

Effects of Mo addition on microstructure of a 4th generation Ni-based single crystal superalloy

The effects of Mo addition on the microstructure of a 4th generation Ni-based single crystal superalloy were investigated. Mo addition significantly promoted elements Mo, W and Re partition into γ phase and enhanced absolute lattice misfit at 1100 ​°C. The increase of Mo concentration from 2 ​wt% to 4 ​wt% also decreased the content of eutectic islands and the segregation ratios of other alloying elements in the as-cast state, especially Re and W. After heat treatments, the size of γ′ phase and width of γ channels decreased slightly with higher Mo content. More Mo additions slightly enhanced the segregation behavior of Re while reducing the segregation behavior of Mo. However, it revealed that the primary and secondary dendrite arm spacings were barely affected by Mo addition.

Dendrite morphology in Al-20 wt%Cu hypoeutectic alloys in 24 T high magnetic field quantified by ex-situ X-ray tomography

The morphology of the primary α-Al crystal in a solidifying Al-20 wt%Cu alloy under the high static magnetic field (HMSF) was studied by using the ex-situ X-ray computed tomography technique. The side arms were the seaweed and the dendrite under 0 T and 24 T HSMF, respectively. They were identified by 2D slices and 3D reconstruction of dendrites. The secondary dendrite arm spacing increased and the interface curvatures decreased under the HSMF. The growth angle between the secondary dendrite arms and their stems was close to 90° in the case of the 24 T HSMF. These were attributed to the decrease of constitutional supercooling caused by magnetohydrodynamic effect.