Solidification Of Melt Research Articles

Effect of Inherent Mg/Ti Interface Structure on Element Segregation and Bonding Behavior: An Ab Initio Study

To provide insight into the interface structure in Ti particle-reinforced Mg matrix composites, this study investigates the inherent Mg/Ti interface structure formed during the solidification of supercooled Mg melt on a (0001)Ti substrate using ab initio molecular dynamics (AIMD) simulations and density function theory (DFT) calculation. The resulting interface exhibits an orientation relationship of 0001Mg//0001Ti with a lattice mismatch of approximately 8%. Detailed characterizations reveal the occurrences of 0001Mg plane rotation and vacancy formation to overcome the lattice mismatch at the inherent Mg/Ti interface while allowing Mg atoms to occupy the energetically favorable hollow sites above the Ti atomic layer. The atomic diffusion behaviors of rare-earth elements Gd and Y at the Mg/Ti interface was examined using the climbing image nudged elastic band (CI-NEB) method, demonstrating a strong segregation tendency towards the interface promoted by the inherent interface structure. Additionally, the calculated Griffith work indicates enhanced interfacial adhesion due to the segregation of Gd and Y, which is beneficial for the mechanical properties of the composite.

Research on enhancing thermal conductivity of phase change microcapsules with nano-copper

Abstract The unique ability of phase change materials (PCMs) to store and release heat makes their integration into building materials promising for reducing energy consumption and enhancing sustainability. In this work, a novel high-thermal-conductivity microencapsulated phase change material was studied, with nano-copper embedded in the microcapsule structure. This modification enhanced thermal conductivity while largely preserving the material’s latent heat storage capacity. Poly(ethyl acrylate) (PEA) is chosen as the capsule shell, whereas a eutectic mixture of decanoic acid (CA) and lauric acid (LA) serves as the core material. The analysis results indicate that as the shell-core mass ratio decreases, the microcapsule size increases, and both thermal conductivity and thermal diffusivity gradually decrease. Moreover, the latent heat capacity of microencapsulated phase change material (MEPCM) increases. When the shell-core mass ratio is 1:1.5, the melting latent heat and solidification latent heat are 81.85 J g−1 and 88.68 J g−1, respectively. nano-copper doping enhances the material’s thermal conductivity and thermal diffusivity by 47.5% and 50%, respectively, leading to a 20.3% improvement in heat storage efficiency. After 200 cycles of testing, the material maintains good thermal reliability and chemical stability. Mortar-based composite materials containing microcapsules were prepared. The mortar composite materials containing microcapsules exhibited minimal influence from heating and cooling, with those containing nano-copper microcapsules demonstrating superior thermal response speeds. The method of doping and modifying MEPCM with nano-copper is a promising approach for effectively reducing the impact of temperature fluctuations on the internal comfort of buildings, improving energy utilization efficiency, and providing reliable solutions for temperature-sensitive applications.

Magneto‐Optical Control of Ordering Kinetics and Vacancy Behavior in Fe–Al Thin Films Quenched by Laser

One of the issues arising in materials science is the behavior of nonequilibrium point defects in the atomic lattice, which defines the rates of chemical reactions and relaxation processes as well as affects the physical properties of solids. It is previously theoretically predicted that melting and rapid solidification of metals and alloys provide a vacancy concentration in the quenched material, which can be comparable to that quantity at the point of melting. Here, the vacancy behavior is studied experimentally in thin films of the near equiatomic Fe–Al alloy subjected to nanosecond laser annealing with intensities up to film ablation. The effects of laser irradiation are studied by monitoring magneto‐optically the ordering kinetics in the alloy at the very ablation edge, within a narrow (micron‐scale) ring‐shaped region around the ablation zone. Quantitatively, the vacancy supersaturation in the quenched alloy has been estimated by fitting a simulated temporal evolution of the long‐range chemical order to the obtained experimental data. Laser quenching (LQ) of alloys and single‐element materials will be a tool for obtaining novel phase states within a small volume of the crystal.

Phase transformations of ternary copper iron sulfide Cu1.1Fe1.9S3.0 under temperature variations: thermodynamic and kinetic aspects

The article considers ternary sulfide Cu1.1Fe1.9S3 with a metal/sulfur ratio corresponding to the complete stoichiometry of cubanite CuFe2S3 as an intermediate phase of a solid solution with chemically disordered Cu and Fe cations in the ordered anionic framework. A new approach to determining the nature of the solid solution, its stability and behavior during cooled over a wide temperature and time range is suggested. To synthesize the sample, we used controlled directional solidification of a homogeneous melt with the Cu1.1Fe1.9S3 composition under quasi-equilibrium conditions and obtained a solidified zoned ingot, where the distribution of Cu, Fe, and S elements along its length was quantitatively determined. To detect small-scale structural and chemical changes, we used optical and electron microscopy methods, electron-probe X-ray spectral microanalysis, full-profile X-ray diffraction analysis, and the differential dissolution method, which allowed to determine the phase and chemical states of the samples both at the macro level and with a high spatial resolution. With this approach, we established the following: Cu1.1Fe1.9S3 is an intermediate phase of a system with end-members of cubanite CuFe2S3 and chalcopyrite CuFeS2; a homogeneous solid solution of chalcopyrite with 5 mol. % of cubanite exists near 930 °С with a chaotic distribution of Cu and Fe between the existing crystallographic positions; a solid solution of chalcopyrite with 6 mol. % of cubanite at 900 °С facilitates lattice strain relaxation through the formation of a block nanostructure; there is a solid solution of cubanite with 30 mol. % of chalcopyrite at 900–720 °С, with small-size clusters with a chalcopyrite stoichiometry evenly distributed inside the Cu0.94Fe2S3 matrix. The factors determining the evolution and stability of solid solutions are discussed taking into account the polymorphism of chalcopyrite phase. The newly obtained data is important for the synthesis of magnetic nanosized Cu-Fe sulfide materials and can also be used in the processing of sulfide ores rich in copper

A Phase-Field Model for Wet Snow Metamorphism.

The microstructure of snow determines its fundamental properties such as mechanical strength, reflectivity, or thermo-hydraulic properties. Snow undergoes continuous microstructural changes due to local gradients in temperature, humidity, or curvature, in a process known as snow metamorphism. In this work, we focus on wet snow metamorphism, which occurs when the temperature is close to the melting point and involves phase transitions among liquid water, water vapor, and solid ice. We propose a pore-scale phase-field model that simultaneously captures the three relevant phase change phenomena: sublimation (deposition), evaporation (condensation), and melting (solidification). The phase-field formulation allows one to track the temperature evolution among the three phases and the water vapor concentration in the air. Our three-phase model recovers the corresponding two-phase transition model when one phase is not present in the system. 2D simulations of the model unveil the impact of humidity and temperature on the dynamics of wet snow metamorphism at the pore scale. We also explore the role of liquid melt content in controlling the dynamics of snow metamorphism in contrast to the dry regime before percolation onsets. The model can be readily extended to incorporate two-phase flow and may be the basis for investigating other problems involving water phase transitions in a vapor-solid-liquid system, such as airplane icing or thermal spray coating.

Crystallization behavior of BOF slag during the cooling process towards leaching for CO2 sequestration

This work addresses the crystallization behavior and microstructure feature of the molten basic oxygen furnace (BOF) slag during a slow cooling process. The aim is to provide a reference for the modification of BOF slag for subsequent leaching of Ca as part of CO2 sequestration. Integrated analysis of XRD, SEM-EDS, and thermodynamic calculations suggest a crystallization behavior of BOF slag during the cooling process. RO phases ((Mg, Fe, Mn) O) was the equilibrium phase at a high temperature of around 1600 °C, followed at lower temperatures by the formation of Ca3SiO5 (C3S) and α-Ca2SiO4 (α-C2S). The Ca2Fe2O5 (C2F) phase forms during the latter stages of melt solidification. On the basis of the combined analysis of the leaching test results and crystallographic analysis, a future direction of modification of BOF slag is suggested that enriches Ca into the C2S and hinders the formation of C2F. However, inhibiting the generation of C2F by adjusting the cooling process alone is difficult since its crystallization rate is fast. The phase of C2F was observed in XRD and SEM even if the BOF slag was quenched from 1600 °C. Furthermore, the chemical characterization and morphological evolution of the crystalline phase of molten BOF slag during the slow cooling process was observed.

Numerical model for the solidification of a chondrule melt

In this study, we propose a novel numerical method to simulate the growth dynamics of an olivine single crystal within an isolated, multicomponent silicate droplet. We aimed to theoretically replicate the solidification textures observed in chondrules. The method leverages the phase-field model, a well-established framework for simulating alloy solidification. This approach enables the calculation of the solidification process within the ternary MgO–FeO–SiO2 system. Furthermore, the model incorporates the anisotropic characteristics of interface free energy and growth kinetics inherent to the crystal structure. Here we investigated an anisotropy model capable of reproducing the experimentally observed dependence of the growth patterns of the olivine single crystal on the degree of supercooling under the constraints of two-dimensional modeling. By independently adjusting the degree of anisotropies of interface free energy and growth kinetics, we successfully achieved the qualitative replication of diverse olivine crystal morphologies, ranging from polyhedral shapes at low supercooling to elongated, needle-like structures at high supercooling. This computationally driven method offers a unique and groundbreaking approach for theoretically reproducing the solidification textures of chondrules.

In Situ Observation of Precipitation Behavior of MnS during Solidification of Steel Melt Intended for Production of Nonquenched and Tempered Steel

Two heats of steel are melted using a vacuum induction furnace in the laboratory, with one heat undergoing magnesium treatment and the other being subjected to a combined magnesium–calcium treatment. The precipitation and agglomeration behaviors of inclusions of these two steel samples are observed using a high‐temperature confocal laser scanning microscopy. MnS precipitates form around oxide cores and undergo rapid growth during the solidification process of molten steel, and these MnS precipitates with oxide cores react with the cores, resulting in the transformation of the MnS into complex sulfides. In comparison with Al2O3 inclusions, MgO·Al2O3 inclusions have a lower critical velocity (V c), making them more susceptible to being engulfed by the solid–liquid interface. As the size of colliding inclusions increases, the coalescence–collision frequency (E 0) initially decreases until it reaches a minimum value. After that, with further size increments, the frequency starts to increase. During the inclusions growth process through collision, there is a distinct zone where coalescence–collision frequency is low. Inclusions that reach this zone struggle to grow further due to reduced collision coalescence, consequently leading to a predominance of inclusions with diameters in this zone.

Ultra-high volume expansion ratio branched PBT/TPEE three-dimensional reticulated foams of supercritical CO2 melt foaming for efficient oil/water separation

The development of polymer reticulated foams with high expansion ratios (VER) for selective oil-adsorption applications has been hindered by technical challenges. In this article, high VER reticulated foam with outstanding selective oil-adsorption performance was realized through the synergistic effect of molecular topological structure and blending heterostructure. Branched polybutylene terephthalate(B-PBT)/thermoplastic polyester elastomer(TPEE) was prepared by blending reaction. Then, B-PBT/TPEE blends were foamed by supercritical CO2 melting foaming, a solvent-free process. The nano-scale TPEE, acting as the weak point, induced the cell wall to rupture and form reticulated foam after the B-PBT had expanded to a high VER. The branching topological structure endowed PBT high storage modulus(G’) and complex viscosity(η*), which support the expansion of foam and keep foam from collapsing before the melt solidification. As a result, ultra-high VER three-dimensional reticulated foams possessing VER of 46.9 and open-cell content of 97.8 % were prepared, which is higher about 200 % than the previous research. The water contact angle of reticulated foams is 132° and cyclohexane droplets diffuse into reticulated foam showing the contact angle of 0°, indicating the reticulated foam have oleophilicity and hydrophobicity. The adsorption capacity of the reticulated foam for various oils is from 24 to 67 g/g. Moreover, the adsorption rate constant of reticulated foam is 8 times more than that of conventional open-cell foam. These benefits from the unique cell structure and high VER of reticulated foam. The work provides a facile and novel method for the green preparation of high-performance oil/water separation materials.

Variation in microstructural features of melt-pool structure in laser powder bed fused Al–Fe–Cu alloy at elevated temperatures

The present study was undertaken to understand the effect of annealing on the microstructural features of the melt-pool structure and the associated multiscale mechanical properties of the Al–2.5%Fe–2%Cu alloy manufactured by laser powder bed fusion (LPBF). Microstructural characterizations and tensile tests were conducted for the LPBF-built specimen and those subsequently annealed at various temperatures ranging from 200 to 500 °C. Nanoindentation hardness mapping was used to evaluate the mechanical inhomogeneity of the melt-pool structure and its changes by annealing at different temperatures. The LPBF-manufactured sample exhibited a melt-pool structure containing numerous particles of the Al23CuFe4 phase (oC28, orthorhombic structure) formed because of local melting and rapid solidification during the LPBF process. The relatively coarsened cellular structure localized along the melt-pool boundary resulted in local soft regions. The local vulnerability contributed to the direction dependence of the tensile ductility. A slight variation was observed in the inhomogeneous microstructure of the samples annealed at 200 or 300 °C. The formation of numerous Al23CuFe4 nanoprecipitates in the α-Al supersaturated solid solution prevented strength loss after post-heat treatments. In addition, considerable coarsening of the intermetallic phase after annealing at 500 °C eliminated the melt-pool structure. The tensile performance of the specimens demonstrated a ductile fracture mode, wherein ductile fracture occurred in the α-Al matrix with low hardness while the harder θ-Al13Fe4 stable phase was embedded within it. The anisotropy in the mechanical properties was less pronounced owing to the significant microstructural changes.

The temperature field characteristics and amorphous formation ability during the continuous casting process of Zr-based bulk metallic glass

This study utilized FLUENT dynamic mesh simulation technology to simulate the temperature field distribution characteristics during the continuous casting (CC) process of 5 mm thick Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 (Vit1) bulk metallic glass (BMG), analyzed and discussed the amorphous forming ability of the Vit1 BMG plate prepared through CC. The results indicate that during the CC process, the temperature gradient and cooling rate of Vit1 BMG plate decrease with increasing distance from the cooling copper block surface and prolonged solidification time. Even at the lowest cooling rate, it still remains significantly higher than the critical cooling rate (Rc) of Vit1 bulk amorphous alloy. The temperature variations recorded by the thermocouple during the alloy melt solidification process are in basic agreement with the simulation data. The experimental test and simulation results show that 5 mm thick Vit1 BMG slab can be prepared theoretically by continuous casting technology. Finally, XRD, DSC and TEM were used to analyze the amorphous formation ability and microstructure of the Vit1 BMG slab.

Strength and plasticity improvement induced by strong grain refinement after Zr alloying in selective laser-melted AlSiMg1.4 alloy

In order to enhance the mechanical properties of the selective laser-melted (SLM) high-Mg content AlSiMg1.4 alloy, the Zr element was introduced. The influence of Zr alloying on the processability, microstructure, and mechanical properties of the alloy was systematically investigated through performing microstructure analysis and tensile testing. It was demonstrated that the SLM-fabricated AlSiMg1.4−Zr alloy exhibited high process stability with a relative density of over 99.5% at various process parameters. Besides, the strong grain refinement induced by the primary Al3Zr particle during the melt solidification process simultaneously enhanced both the strength and plasticity of the alloy. The values for the yield strength, ultimate tensile strength, and elongation of the SLM-fabricated AlSiMg1.4−Zr were (343±3) MPa, (485±4) MPa, and (10.2±0.2)%, respectively, demonstrating good strength− plasticity synergy in comparison to the AlSiMg1.4 and other Al−Si-based alloys fabricated by SLM.

Thermal Performance Improvement of Composite Phase-Change Storage Material of Octanoic Acid–Tetradecanol by Modified Expanded Graphite

Phase-change cold storage technology is recommended as a solution for energy conservation and carbon neutrality in air conditioning systems of buildings. This study focuses on the development of binary composite phase-change materials comprising octanoic acid–tetradecanol (OA-TD). To enhance its thermal conductivity, expanded graphite (EG) was employed as an additive carrier, and the surface modification of EG particles using hexadecyltrimethoxysilane (HDTMOS) was attempted to make up for the instability and further to improve the performance of OA-TD/EG CPCMs. The OA-TD/EG-HDTMOS CPCMs were synthesized by EG mixed with EG-HDTMOS at a 1:1 mass ratio. The thermal performance and stability of the OA-TD/EG-HDTMOS CPCMs were thoroughly evaluated by multi-cycle melting–solidification and thermal conductivity measurements. The results revealed that the OA-TD mixture, when at a mass ratio of 77:23, exhibited a phase-transition temperature of 11.4 °C and a latent heat ranging from 150 to 155 J/g. Then, the OA-TD/EG-HDTMOS composite material, at a 12:1 mass ratio of OA-TD to EG-HDTMOS, solidified and melted at temperatures of 9.2 °C and 11.2 °C, with a latent heat ranging from 138 to 143 J/g, and significantly improved the thermal conductivity to 0.7 W/(m·K), representing a remarkable 133% increase compared to that of OA-TD alone. Even after undergoing 100 melting–solidification cycles, the OA-TD/EG-HDTMOS maintained superior phase-change thermal performance and stability, making it suitable for cold storage and energy conservation in air conditioning.

Influence of Mg Content on Microstructure Coarsening, Molten Pool Size, and Hardness of Laser Remelted Al(-x)-Mg-Sc Alloys.

Investigations leading to high-quality surfaces and optimized properties in laser remelted Al-Mg-Sc alloys remain scarce. Laser surface remelting (LSR) has been used for the final treatment of these alloys processed through additive manufacturing. However, the direct microstructure responses of the treated cast surfaces have not yet been investigated. In the present research, Al-3, 5, and 10 wt %-Mg-0.1 wt %-Sc alloys plates were processed using LSR to study the effects of local melting and rapid solidification. The morphology of the α-Al phase, microstructure coarsening, and hardness were mapped from the bottom to the top of the molten pools, varying with local Mg content and laser heat input (2.5 J/mm, 5 J/mm, and 10 J/mm). This study aimed to create a comprehensive map of the microstructures, hardness, and molten pool sizes under various conditions. The findings may help to optimize these alloys through understanding laser processing parameters. Methods used included CALPHAD computations, optical microscopy, SEM, EDS, image analysis, hardness tests, and heat flow models. The results obtained showed α-Al cell growth with bands in all alloys with hardness changes correlating with cell spacing and heat input. Higher Mg content resulted in more refined cells and a higher fraction of bands. Increased Mg content decreased the thermal diffusivity and enthalpy of melting, enlarging the molten pool size. Hardness increased with decreasing heat input and higher Mg content in the tested alloys, especially in the Al-10 wt %-Mg-0.1 wt %-Sc alloy as the heat input was varied.

Optimizing Selective Laser Melting of Inconel 625 Superalloy Through Statistical Analysis of Surface and Volumetric Defects

This article delves into optimizing and modeling the input parameters for the selective laser melting (SLM) process on Inconel 625. The primary aim is to investigate the microstructure within the interlayer regions post-process optimization. For this study, 100 layers with a thickness of 40 µm each were produced. Utilizing the design of experiments (DOE) methodology and employing the Response Surface Method (RSM), the SLM process was optimized. Input parameters such as laser power (LP) and hatch distance (HD) were considered, while changes in microhardness and roughness, Ra, were taken as the responses. Sample microstructure and surface alterations were assessed via scanning electron microscopy (SEM) analysis to ascertain how many defects and properties of Inconel 625 can be controlled using DOE. Porosity and lack of fusion, which were due to rapid post-powder melting solidification, prompted detailed analysis of the flaws both on the surfaces of and in terms of the internal aspects of the samples. An understanding of the formation of these imperfections can help refine the process for enhanced integrity and performance of Inconel 625 printed material. Even slight directional changes in the columnar dendrite structures are discernible within the layers. The microstructural characteristics observed in these samples are directly related to the parameters of the SLM process. In this study, the bulk samples achieved a microhardness of 452 HV, with the minimum surface roughness recorded at 9.9 µm. The objective of this research was to use the Response Surface Method (RSM) to optimize the parameters to result in the minimum surface roughness and maximum microhardness of the samples.

Process exploration for scale melting and solidifying of municipal solid waste incineration (MSWI) fly ash by horizontal cyclone melting furnace

This study used the horizontal tubular heating furnace to explore the melting potential of circulating fluidized bed (CFB) incinerator fly ash and mechanical grate furnace (MGF) incinerator fly ash. The horizontal cyclone melting furnace was then built to explore further the feasibility of scale melting of MSWI fly ash. The melting characteristic temperature, amorphous content, and heavy metal leaching concentration characterized the melting potential and solidification effect of MSWI fly ash. The experimental results show that the amorphous content of CFB fly ash after melting is up to 92.37%, and the volatilization rate of heavy metals Zn, Pb, and Ni does not exceed 30%. MGF fly ash exhibits the “sintering into shells” phenomenon during heating, and the leaching concentrations of heavy metals Pb in the sintered products still exceed the standard limits. In addition, the volatilization rates of heavy metals Cu, Zn, Cd, Pb, Cr, and Ni in Slag II are above 50%, and the volatilization rate of Cr reaches 85%. So, slag’s amorphous content also affects heavy metals’ volatilization rate. The MSWI fly ash melting characteristic temperature decreases with the decrease of alkalinity value. When the alkalinity value drops to 0.6, the melting characteristic temperature reaches its lowest value. Mixing 80% CFB fly ash or 50% MGF bottom ash into MGF fly ash can significantly enhance the melting potential to reduce hazardous waste. When using the horizontal cyclone melting furnace to process MSWI fly ash on a large scale, MSWI fly ash achieves an excellent melting effect with an amorphous content of over 93% at the positions of the furnace middle section, inner tail cone, slag discharge outlet, and flue gas outlet. The fly ash particles are in motion in the melting furnace, so the particle size distribution affects the melting effect of MSWI fly ash.

Application of Numerical Modeling and Finite Element Analysis in Fused Filament Fabrication: A Review.

Additive manufacturing (AM) is not necessarily a new process but an advanced method for manufacturing complex three-dimensional (3D) parts. Among the several advantages of AM are the affordable cost, capability of building objects with complex structures for small-batch production, and raw material versatility. There are several sub-categories of AM, among which is fused filament fabrication (FFF), also commonly known as fused deposition modeling (FDM). FFF has been one of the most widely used additive manufacturing techniques due to its cost-efficiency, simplicity, and widespread availability. The FFF process is mainly used to create 3D parts made of thermoplastic polymers, and complex physical phenomena such as melt flow, heat transfer, solidification, crystallization, etc. are involved in the FFF process. Different techniques have been developed and employed to analyze these phenomena, including experimental, analytical, numerical, and finite element analysis (FEA). This study specifically aims to provide a comprehensive review of the developed numerical models and simulation tools used to analyze melt flow behavior, heat transfer, crystallization and solidification kinetics, structural analysis, and the material characterization of polymeric components in the FFF process. The strengths and weaknesses of these numerical models are discussed, simplifications and assumptions are highlighted, and an outlook on future work in the numerical modeling and FE simulation of FFF is provided.

High-speed synchrotron X-ray imaging of melt pool dynamics during ultrasonic melt processing of Al6061

Ultrasonic processing of solidifying metals in additive manufacturing can provide grain refinement and advantageous mechanical properties. However, the specific physical mechanisms of microstructural refinement relevant to laser-based additive manufacturing have not been directly observed because of sub-millimeter length scales and rapid solidification rates associated with melt pools. Here, high-speed synchrotron X-ray imaging is used to observe the effect of ultrasonic vibration directly on melt pool dynamics and solidification of Al6061 alloy. The high temporal and spatial resolution enabled direct observation of cavitation effects driven by a 20.2 kHz ultrasonic source. We utilized multiphysics simulations to validate the postulated connection between ultrasonic treatment and solidification. The X-ray results show a decrease in melt pool and keyhole depth fluctuations during melting and promotion of pore migration toward the melt pool surface with applied sonication. Additionally, the simulation results reveal increased localized melt pool flow velocity, cooling rates, and thermal gradients with applied sonication. This work shows how ultrasonic treatment can impact melt pools and its potential for improving part quality.

Inhomogeneous deformation in melt-pool structure of Al-Fe-Cu alloy manufactured by laser powder bed fusion

Abstract The laser powder bed fusion (L-PBF) processed Al–2.5Fe–2Cu (mass%) alloy exhibited a high tensile strength above 340 MPa and pronounced directional dependence. The sample exhibited a characteristic inhomogeneous microstructure (in melt-pool structure) arising from the local melting and rapid solidification in the L-PBF process. The coarsened cellular structure localized along the melt pool boundary resulted in the local soft regions affected by the melt pool structure. The local vulnerability contributed to the direction dependence of the tensile ductility of the specimen.

An exploratory study on miniaturized additive friction stir deposition

Without melting and rapid solidification, additive friction stir deposition offers a deformation processing route to additive manufacturing and repair of high-performance alloys with full density and desirable properties. However, this approach has traditionally relied on expensive and bulky equipment, posing challenges for small-feature creation and portability. Here, we explore miniaturized additive friction stir deposition by modifying an affordable benchtop mill and introducing innovative tool design. With in situ monitoring of temperature and force evolution, we demonstrate the efficacy of this approach by dissimilar metal printing, depositing high-strength martensite steel (AISI 4140) onto mild steel (AISI 1018). Compared to conventional facilities, the present approach reduces the in-plane dimension of the feed-rod by a factor of three and narrows the deposition tracks to a few millimeters in width. The as-deposited steel exhibits full density and retains martensitic characteristics without forming new phases at the interfacial region. The as-deposited steel shows significant microstructure refinement with increased hardness because of the extreme thermomechanical conditions during deposition. We discuss the influences of downsizing on the thermal and mechanical aspects of deposition. Owing to the size effects in heat generation and heat loss, the rotation rate of the print head needs to be significantly increased in miniaturized additive friction stir deposition to ensure good deposition quality. To prevent buckling, the unsupported length of the feed-rod should be reduced in proportion to its in-plane dimension.