As-cast Structure Research Articles

Enhanced tensile properties of as-cast Mg-10Al magnesium alloy via strontium addition and hot working

The lightweight magnesium–aluminum alloys are extensively used in automotive and aerospace industries due to their high-specific strength and low alloying cost, Grain refining via alloying and hot deformation is known as a viable technique for the enhancement of mechanical properties of these alloys. Accordingly, in the present work, grain size refinement and improvement of tensile properties of Mg-10Al magnesium alloy ingot via strontium addition (up to 1 wt%) and hot working (extrusion process) were studied. It was revealed that the addition of Sr up to 0.05 wt% leads to grain refinement of Mg-Al-Sr alloys with the resulting best strength-ductility combination. The as-cast alloys were quite brittle with total elongations well below 5% and their ultimate tensile strength (UTS) values were below 200 MPa, which was attributed to the coarse as-cast structure with a high content of brittle intergranular β-Mg17Al12 phase. It was also found that the aspect ratio of the Al4Sr particles increases by increasing strontium content, which contributes to the deterioration of tensile properties at high strontium contents. Homogenization treatment at elevated temperatures led to the dissolution of the β phase, while the thermally stable Al4Sr particles remained undissolved. The extruded alloys showed remarkably higher strength and ductility compared to the as-cast ingots, which were related to the remarkable grain refinement induced by the recrystallization processes during the hot extrusion process, the disappearance of the deleterious network of the intergranular eutectic constituent, and providing high solute Al content. As a result, UTS of ~ 406 MPa and total elongation of ~ 24% were obtained for the extruded alloy with 0.05 wt% Sr.

Initiation of Dynamic Recrystallization of As-Cast N08028 Alloy

The use of high nickel content austenitic stainless steels (SASS) has significantly increased in the last decade. The corrosion and high fatigue resistance of these materials make them suitable for manufacturing oil country tubular goods (OCTG). SASS are processing by forging from casting conditions. Dynamic recovery (DRV) and recrystallization (DRX) of as-cast super austenitic stainless steel, N08028 Alloy, is investigated to study the refining effect from the as-cast grain structure to fully recrystallized austenite due to hot deformation. Both the critical stress and strain for the initiation of DRX are determined using the flow curves. To perform this analysis, hot compression tests are performed at temperatures between 900°C and 1250°C, and strain rates between 0.1 s-1 and 10 s-1, up to 0,8 final strain using a Gleeble®3800 thermomechanical simulator. Subsequently, the Johnson-Avrami-Mehl-Kolmogorow (JMAK) model is used to numerically fit the flow curves and consequently determine the critical strain. No critical points are seen for temperatures under 1100°C. Above this temperature, the JMAK model proves to be valid in all studied strain rates.

Investigation of the Intermetallic Compounds Fragmentation Impact on the Formation of Texture during the as Cast Structure Thermomechanical Treatment of Aluminum Alloys

In this work, the influence of the intermetallic particle fragmentation during hot rolling of the as cast structure on the evolution of textures in aluminum alloys 8011, 5182 and 1565 was investigated. For this purpose, laboratory multi-pass rolling of the cast material was carried out. At various degrees of hot rolling deformation, the process was stopped, and the metal was quenched and sent for optical and electron microscopy to investigate the large intermetallic particles. In addition, the grain structure was studied and an X-ray analysis was carried out in order to determine the main texture components. Some of the samples were held at a temperature above the recrystallization threshold and then cooled in air; the grain structure and texture composition were also studied. In addition, the simulation of the texture evolution was carried out under various modes of rolling of aluminum alloys, taking into account the process of fragmentation of intermetallic particles. The investigation showed that intermetallic compounds with a deformation degree of 1.8, on average, decrease the particle size by 5–7 times. The large eutectic particles remaining after homogenization are drawn out in the direction of deformation and are crushed, increasing their number accordingly. Therefore, the most favorable stage for the formation of recrystallization nuclei on particles is the moment when they are already numerous and their sizes are much larger than subgrains. Simulation of hot rolling of the investigated alloys showed that considering the factor of fragmentation of intermetallic particles during hot deformation of the as-cast structure significantly increases the accuracy of the results.

Temperature–Time–Transformation Diagrams Construction for Beta-Solidifying TiAl-Based Alloy in As-Cast Condition

An experimental investigation of structure evolution kinetics in a new six-component TiAl-based alloy Ti-44.5Al-2V-1Nb-(0.5…L5)Zr/(L5…2.5)Cr-(0…0.1Gd) (at.%) with variable Zr, Cr, and Gd content has been accomplished under the conditions of high-temperature exposures in the temperature range 1000–1300°C and durations of 15–240 min. The Temperature – Time – Transformation diagrams have been constructed to summarize data on isothermal phase transformations for both Zr(+Gd)- and Cr(+Gd)-containing compositions with the initial as-cast structure. It is shown that the variation of Zr and Cr contents within the given limits for the studied alloy, as well as the doping with Gd microadditions in the amount of 0.1 at.% do not lead to any noticeable effect on the kinetics of structure behavior in isothermal conditions.

Effect of Mn Addition on Hot-Working Behavior and Microstructure of Hot-Rolled Medium-Mn Steels

Hot plastic working behavior and microstructure evolution were investigated during a production process of four medium-Mn steels, which differed in Mn (3 and 5%) and Nb contents. The production process started with casting, followed by hot forging, rough hot-rolling and concluded with final thermomechanical processing, which was performed to obtain multiphase bainite-based alloys with some fractions of retained austenite. The rough rolling was composed of four passes with total true strain of 0.99 and finishing rolling temperature of 850 °C, whereas thermomechanical processing contained five passes and total true strain of 0.95 at a finishing rolling temperature of 750 °C. During the process, the force parameters were recorded, which showed that the rolling forces for steels containing 3% Mn are higher compared to the 5% Mn alloys. There was no significant influence of Nb on the rolling parameters. The produced as-cast microstructures were composed of dendritic bainitic-martensitic phases. A positive effect of Nb micro-addition on a refinement of the as-cast structure was noticed. The thermomechanical processed steels showed fine multiphase microstructures with some fractions of retained austenite, the fraction of which depended on the Mn content in steel. The steels containing 3% Mn generated higher forces both during rough and thermomechanical rolling, which is related to slower recrystallization softening in these alloys compared to the steels containing 5% Mn.

Interface characteristics between TiN and matrix and their effect on solidification structure

Heterogeneous nucleation is an effective way to promote the dispersion and precipitation of second-phase particles in steel and refine the grain size of the solidification structure. Not only refining as-cast structure grain size, but TiN in ferritic stainless steel can also pin grain boundaries and restrain the overgrowth of grains during rolling. The interface characteristics between TiN and heterogeneous phases (high-melting inclusions and ferrite phase) were studied based on the wetting angles between molten steel with different compositions and TiN substrate, and on the matching degree between TiN and ferrite lattice. It was found that, for the molten steel with the same composition, the wetting angle with the TiN substrate was significantly smaller than the contact angles with the other three substrates, while the wetting angle between ferrite phase and TiN was the smallest. The lattice matching was compared among MgAl2O4, TiN and δ matrix by means of a high-resolution transmission electron microscope, which revealed that a coherent or semi-coherent interface was formed between the crystal plane (400) of MgAl2O4 and the crystal plane (200) of TiN, as well as between the crystal plane (200) of TiN and the crystal plane (110) of δ matrix, with a lattice misfit of 5.1% and 3.4%, respectively. Finally, these two characteristics between TiN and ferrite phase were both explained from the perspective of interfacial energy. The microstructure refinement mechanism from high temperature to room temperature can be better reflected by the proposed wetting–lattice misfit theory.

Study of recrystallization kinetics of aluminium alloy 1565ch with low degree of cast structure conditioning

The present study addresses recrystallization process in Al – Mg 1565ch system alloy samples (Russian classification). The samples are taken from cast ingot, produced by continuous casting in DC mold and homogenized based on standard commercial mode. Then the samples were heated to 350–500 oC and rolled in lab mill with different process schedules to cover the entire range of temperature and strain rates, applied in rolling. After rolling the samples were annealed at 350, 400 and 450 oC, their resultant microstructure was examined by optic microscope. The rate of new grains nucleation, their growth speed, analytical notations, describing recrystallization kinetics, were obtained within the frames of the study to be applied during this alloy recrystallization modelling; the main alloy-specific recrystallization features were identified and compared with alloy АА5182 (classification of American Aluminum Association). It is demonstrated, that 1565ch recrystallization has a number of specific features in case of as-cast structure deformation with low strain levels (ε = 0.14÷0.56): first, high rate of new grains nucleation; second, low grain growth speed to the extent of complete process blocking. Optimal recrystallization temperature is identified as 400 oC, at this temperature the process is over 75% complete, the temperature drop (350 oC) causes incubation period extension, while recrystallization subsides at recrystallized structure volume of about 30%, in case of temperature rise (450 oC) the structure is saturated with fine new grains nuclei, probably, emerging during heating, but due to high intensity of recovery and polygonization, recrystallization driving force drops to zero, the process stops with mixed structure and max recrystallized grains volume of 20%. This research was funded through a grant by the Russian Science Foundation, Project 18-79-10099.

Comparative analysis of structure evolution and thermal stability of сommercial AA2219 and model Al-2 wt%Mn-2 wt%Cu cold rolled alloys

Cold-rolled commercial AA2219 and model Al-2 wt%Mn-2 wt%Cu(2Mn2Cu) alloys have been compared in phase composition, microstructure, physical and mechanical properties after different heat treatment routes. The as-cast structure of the model alloy proves to be similar to the homogenized structure of the branded alloy, providing a far shorter technological route required for obtaining a 95% cold reduction ratio. The principal possibility of obtaining cold rolled sheet products with a sufficiently high set of mechanical properties and electrical conductivity without the necessity of homogenization annealing, solution treatment, and water quenching has been shown. Electron microscopy, X-ray diffraction and Thermo-Calc software simulation have been used for optimizing the alloy composition. It has been shown that the as-cast structure of the model alloy has the minimum quantity of Al2Cu eutectic inclusions, and almost all manganese content and about 1.2% Cu are dissolved in the aluminum solid solution. This structure provides for a high plasticity that allows for deformation of ingots without their preliminary homogenization. The formation of the Al20Cu2Mn3 nano-sized dispersoids (with volume fraction of about 7 vol%) has been found to provide for the retaining of the fiber-like (non-recrystallized) grain structure in the model 2Mn2Cu alloy after annealing at 400 °С (3 h), despite a very high cold rolling reduction ratio (95%). The model alloy exhibits a substantially higher strength performance after annealing at 400 °С in comparison with the AA2219 alloy. For example, the YS value of the model alloy is 210 vs 86 MPa. This indicates a higher tolerance of the model alloy toward softening. Summing up the results, the ternary 2Mn2Cu model alloy shows a potential to become the basis for designing new high-tech heat-resistant alloys as a sustainable alternative to 2xxx alloys.

Effect of solutionizing temperature on the microstructural evolution during double aging of powder bed fusion-additive manufactured IN718 alloy

Quantitative microstructural analysis was carried out to determine the size and volume fraction of strengthening phases: gamma double prime (γ″) and gamma prime (γ′); in additively manufactured (AM) Inconel 718 (IN718) with an emphasis on the utilization of Nb for γ″ formation during aging treatment. Powder bed fusion AM (PBF-AM) technique was used to generate coupons using indigenously synthesized IN718 alloy powder. Microstructural studies using transmission electron microscope (TEM) and small angle x-ray scattering (SAXS) were carried out on powder bed fusion-additive manufactured (PBF-AM) coupons in as-built condition (as processed) and in three different heat-treated conditions: solutionizing at three different temperatures (980, 1030 and 1080 °C) followed by double aging treatment. As-built microstructure consists of dendritic structure accompanied with Nb segregation along the interdendritic regions resulting in the formation of a Nb rich interdendritic phases dispersed within the interdendritic Nb-rich γ matrix. The inhomogeneous Nb distribution resulted in preferential precipitation of coarse δ during solutionization at 980 °C and further coarse γ″during direct aging and aging subsequent to solutionizing at 1030 °C. As-cast structure and related elemental segregation got modified during solutionization at 1080 °C and resulted homogeneous γ″ precipitation. Though the average size of γ″precipitates remained same in all aged samples, volume fraction increased with increasing solutionization temperature. SAXS studies were carried out on PBF-AM as well as conventionally produced wrought samples with the similar heat treatment conditions and confirmed that PBF-AM built IN718 aged samples solutionized at 1030 °C and 1080 °C resulted in γ″ precipitates with average precipitate size and volume fraction similar to that of the wrought-IN718 sample solutionized at 1080 °C.

Effect of samarium on the high temperature tensile properties and fracture behaviors of Al–Zn–Mg–Cu–Zr alloy

The Al-6.7Zn-2.6Mg-2.0Cu-0.1Zr alloy is modified by Sm for the purpose of improving its mechanical properties at high temperatures. According to the results, the as-cast structure can be refined through 0.3% Sm modification treatment, and finer precipitates can be obtained after aging. In the meantime, with the addition of Sm, a new high melting point Al10Cu7Sm2 phase is formed, the initial decomposition temperature of the alloy is raised, and the thermal stability is enhanced. As indicated by the tensile test results at room temperature and high temperatures, the strength of the modified sample was improved compared with the unmodified alloy. According to fracture surface analysis, ductile fracture conforms to the fracture characteristic exhibited by the modified alloy at room temperature and high temperatures. The improvement on high temperature strength of the modified alloy is attributed largely to a combination of grain refinement, precipitation strengthening and heat resistant phase to grain boundary pinning.

Enhancement of strength mechanical and corrosion resistance of 7055 alloy with minor Sc and Y addition

A new type of 7055-Y-Sc alloy with high strength and corrosion resistance was prepared. Eutectic Al3Y particles with sizes in the range of 500–600 nm were found in the as-cast structure of the 7055-Y-Sc alloys. The addition of Y significantly accelerated the precipitation of Al3Zr with L12 structure in Al–Zr–Y alloy, and the number density of Al3 (Zr, Y) precipitates was almost a grade higher than that of Al3Zr. In the process of aging at 120 ℃/12 h, the nano scale L12-type Al3 (Sc x Y y ) phase nucleated uniformly within the Al matrix and nonuniformly on the dislocation. The grain size decreased from 100–200 um in 7055-Y-0Sc to 40–50 um in 7055-Y-0.25Sc, the percentage of Sc continued to increase, and the grain size remained unchanged or even increased, thereby decreasing the Vickers hardness of 7055-Y-Sc alloys from 196.4 HV to 187.9 HV. After aging, the hardness and tensile properties of 7055-Y-Sc alloy showed good performance. The effective Sc proportion of the 7055-Y-Sc alloy was 0.25%. Its tensile strength was 398.6 MPa. Its conductivity was 33.8% IACS. The current corrosion density was 6.7 × 10−8 A cm−2, its good strength, corrosion resistance and conductivity make the studied alloy to be a promising material.

Leveraging Grain Size Effects on Hydrogen Generated via Doped Aluminum–Water Reactions Enabled by a Liquid Metal

Through the aluminum–water reaction, hydrogen is densely stored and generated on-demand. To enable the reaction, we harness eutectic gallium–indium which permeates through aluminum’s grain boundaries, disrupting aluminum’s oxide layer and inhibiting further passivation of the aluminum grain surfaces. We find that, in addition to doping, grain refining and grain coarsening offer a latitude in engineering aluminum microstructures to tune hydrogen generation rates and reaction efficiency. In Mg-doped, Mg2Si-doped, and pure aluminum, reducing the grain size from an as-cast structure to around 30 μm increases the rate of hydrogen flux by an order of magnitude. Mild silicon doping at 0.6 wt % significantly increases the reaction rate in which the same grain size reduction increases hydrogen flux rates by two orders of magnitude. Additionally, the byproduct of the aluminum–water reaction varies with both doping and grain size. Results of combined grain size and doping effects on hydrogen evolution rates allow for further exploration into the underlying reaction mechanism in the presence of a liquid metal.

Superplastic behavior of a nickel-base superalloy containing topologically close-packed phases

Superplastic behaviour of a polycrystalline nickel-base superalloy Ni-47(Cr,Co,W,Al,Ta,Hf)-0.2(C,B) (wt.%) in the fine-grained condition obtained via thermomechanical treatment (TMT) has been studied. TMT transformed a coarse-grained as-cast structure into a homogeneous fine-grained one. Both the initial as-cast and the thermomechanically treated conditions contained not only the matrix γ phase, the hardening γ’ phase and carbides but also topologically close-packed (TCP) phases. In spite of the presence of the TCP phases, the superalloy in the fine-grained condition demonstrated superplastic properties (δ>300% and low flow stresses) at subsolvus temperatures. Superplastic deformation led to some refinement and alignment of the TCP phase particles along the tensile axis.

Correlation between Microstructural Characteristics and Corrosion Properties of Mg-RE Alloys in Ringer’s Solution

The effects of aging heat-treatment and cooling rate from annealing temperature on the microstructure and corrosion properties of a cast Mg-5Gd-2.5Nd-0.5Zn-0.5Zr alloy were studied. The as-cast structure comprised Gd/Nd-rich eutectic phases in α-Mg grain boundaries. In water-quenched and aged specimens, fine Zn/Zr-rich precipitates were developed in the matrix. Furnace cooling caused a significant increase in the volume fraction of both fine and coarse precipitates because of the large difference between the solubility of alloying elements at elevated and room temperatures. Immersion tests for up to 240 h in Ringer’s solution showed a respective corrosion rate of 0.84, 0.73, 0.41, and 0.39 mm y−1 for the furnace-cooled, as-cast, water-quenched, and aged samples. The corrosion behavior was further studied by electrochemical impedance spectroscopy and polarization measurements after 1 and 24 h of immersion in the solution. An increase in the volume fraction of Gd/Nd-rich phases led to a decrease in the corrosion resistance. Large second phases acted as cathodic sites for galvanic corrosion and also locally disturbed the protectiveness of the Mg(OH)2 passive film. Rare earth elements in solid-solution were less detrimental to the corrosion resistance. Less severe corrosion resulted according to SEM observations in the aged and water-quenched samples.

Effect of As-Cast Structure and Macrosegregation on Mechanical Properties in Direct-Quenched Low-Alloy Ultrahigh-Strength Steel

The effect of as-cast structure and macrosegregation on the mechanical properties of a direct-quenched low-alloy martensitic ultrahigh-strength aluminum killed and calcium treated steel cast at different superheats was studied. Samples from the castings were laboratory hot rolled with two different finishing rolling temperatures to distinguish the effect of hot rolling. Using optical emission spectrometry, the steel composition was analyzed as a function of slab thickness in order to detect the variations in steel chemistry due to macrosegregation. Further, hardness profiles, prior austenite grain sizes and tensile and impact toughness were determined for the hot-rolled specimens. It was found that interdendritic segregation was more intense at the higher superheat, which led to more pronounced positive segregation in the columnar-to-equiaxed transition (CET) zone, and negative segregation between CET and the centerline. These macrosegregation patterns were inherited by the hot-rolled samples causing local variations in hardness, which followed the variations in carbon content. However, altering the superheat had a minor effect on the nominal transformed microstructures and nominal prior austenite grain sizes. This occurred because of the interdendritic segregation induced composition variations both enlarged and decreased by turns the grain sizes. The CET also reduced measured impact toughness values.

Effect of Zr Microalloying on the Microstructures and Strengthening Mechanism of As-Cast Al-Fe-Zr Alloys.

The microstructure and mechanical properties of Al-0.35Fe alloys with a series of different zirconium (Zr) additions from 0.1 to 0.4% are investigated by optical microscopy, scanning electron microscopy, transmission electron microscopy and tensile testing. The as-cast structure of the alloys varies with the Zr content. When the content of Zr is 0.1%, Zr dissolves into the aluminum (Al) matrix completely and iron (Fe) concentrates along the boundary in a network of eutectic Al3Fe. With the increase in Zr content to 0.2% and above, nanoscale Al3Zr particles appear in the alloy. With the Zr content increasing from 0.1 to 0.4%, the grain size of the Al matrix decreases from 73 to 23 μm. The morphology of the eutectic Al3Fe phase changes from short rod-like to an agglomerated structure consisting of finer and shorter rod-like shapes. The tensile and yield strengths increase while the total elongation decreases with increasing Zr content. The strengthening mechanism of the alloy can be attributed to the combination of fine-grain, solution and second-phase strengthening.

As-Cast Structure and Temperature Field of Direct-Chill Cast 2024 Alloy Ingot at Different Casting Speeds

The ingot was prepared at different casting speeds, and temperature measurements were taken during the direct-chill (DC) casting process. The results showed that the grain size of the equiaxed grains decreases, the volume fraction of the floating grains increases, and the negative centerline segregation becomes more serious as the casting speed increases. Moreover, the vertical widths and the cooling rates of different regions during the solidification process were analyzed through temperature measurements. At the casting speed of 50 mm/min, the vertical widths of the transition, slurry and mushy regions in the ingot center are relatively small (51, 15, and 36 mm, respectively). As the casting speed increases to 65 mm/min, the vertical widths of the transition, slurry, and mushy regions in the ingot center increase to 70, 29, and 41 mm, respectively. The increase in the vertical width of the slurry region is considered to be the main reason for the increase in the volume fraction of the floating grains. Besides, as the casting speed increases, the cooling rate in the mushy region and the region above the liquidus increases, so the grain size of equiaxed grain decreases.

Effects of thermomechanical treatment on the microstructure, precipitation strengthening, internal friction, and thermal stability of Al–Er-Yb-Sc alloys with good electrical conductivity

Rare-earth elements improve the mechanical properties of aluminum owing to the formation of the L12-structured nanoprecipitates providing the precipitation strengthening effect. The precipitates type, size, and number density depend on the alloy chemical composition and a thermomechanical treatment regime. It is essential to develop the alloys and treatments, providing a combination of the enhanced mechanical strength and a high level of electrical conductivity. This study investigates the influence of thermomechanical treatments on the microstructure, precipitation strengthening, mechanical properties, and electrical conductivity of Al–Er-Yb-Sc alloys with differing Sc content. An as-cast structure of the alloys studied consists of a supersaturated aluminum solid solution and Al3(Er,Yb) phase particles of eutectic origin with the particle thickness of 50–200 nm. A significant strengthening during post-deformation annealing is achieved by precipitation of L12-Al3(Sc,Er,Yb) phase dispersoids of 4–8 nm in size. The mechanical spectroscopy method is successfully used to understand the precipitation kinetics of the studied alloys in comparison with analogous Al-Yb-Y-Sc alloys. This method is highly sensitive to lattice defects parameters, i.e., recrystallization and precipitation kinetics. High-scandium alloys demonstrate an increase of the hardness and tensile strength and insignificant changes in the internal friction background level during post-deformation annealing of cold-worked samples at 300 °C. The yield strength of the Al–Er-Yb-Sc alloys after post-deformation annealing is 142–231 MPa, elongation-to-failure is 3.6–13.5%, and electrical conductivity is 54.8–60.9% IACS, dependent on scandium content and annealing parameters. The studied alloys exhibit high thermal stability of the tensile properties, which remains unchanged during annealing at 300 °C for 100 h.

Effect of Scandium in Al–Sc and Al–Sc–Zr Alloys Under Precipitation Strengthening Mechanism at 350 °C Aging

In the present scenario, it is much needed of developing Al–Sc and Al–Sc–Zr alloys owing to its higher strength to weight for aerospace applications. The present study is dealt about effect of Scandium on micro hardness and micro structure of synthesized Al–Sc alloy and Al–Sc–Zr alloy under different weight percentage. The precipitation strengthening of as-cast structure, Al–Sc alloy and Al–Sc–Zr alloy have been analyzed during aging at 350 °C. From the experimental investigation, only little difference in micro hardness of developed alloys was observed during initial stage of aging. The peak hardness of Al–Sc–Zr alloy was maintained for a relatively longer period for producing better thermal stability. Three-dimensional atomic probing indicated that the precipitation of Zr in the precipitate at the initial stage of aging which can inhibit the growth of the precipitate’s size. TEM results showed that the Al–Sc–Zr alloy formed two precipitates of different sizes at the over-aging phase after the peak state of hardness.

Numerical Assessment of In-Line Rotor\u2013Stator Mixers in High-Shear Melt Conditioning (HSMC) Technology

High shear melt conditioning technology refines the as-cast structure of light alloy melts, thereby improving the mechanical properties of the casting and reducing the occurrence of defects, without requiring chemical grain refiners. To upscale the technology and apply it to processes involving larger melt volumes, a computational fluid dynamics study is conducted with three rotor–stator mixers operating in both batch and continuous modes. Analysis of the results show that rotor–stator mixers with smaller stator holes outperform those with larger ones because of larger shear rates—increasing the deagglomeration rate—and larger volume flow rates—increasing the dispersion of the intensively sheared melt in the bulk liquid. Compared with batch mode, continuous operation results in lower mass flow rate through the mixer and reduced mixing, although the mixer design has a larger impact on both measures.