Tin Powder Research Articles

On the effect of the processing parameters in microstructure and thermomechanical properties of LPBF NiTi shape memory alloys

Recent studies have shown that variations in the parameters of the laser powder bed fusion (LPBF) process significantly impact the microstructure and thermomechanical properties of NiTi shape memory alloys (SMAs). Understanding how parameter selection influences the final NiTi SMA properties enables the strategic design of additively manufactured (AM) components with tailored mechanical and transformation behavior, suitable for specific applications in a plethora of scientific fields. However, the connection between processing and thermomechanical properties of NiTi SMAs is still not completely understood. This study investigates the effects of AM parameters laser power (72–185 W), scanning speed (668-1739 mm/s), and hatch spacing (28–85 μm) on a near equiatomic NiTi powder. Low porosity levels are found in the samples additively manufactured (AM) with the different LPBF parameter combinations. The findings also reveal that transformation temperatures and nickel evaporation trends correlate directly with volumetric energy density (VED). Additionally, the amount of Ti2Ni precipitates increases with higher VED. Thermal cycles under constant stress, training, and two-way shape memory effect tests have been performed; the results demonstrate a strain recovery ratio of 2–3.5% for most of the samples. The results arising from this study pave the way for the engineering of customized materials with tailored properties from the same alloy metal powder.

Formation mechanism of interface layer of ZTA particle reinforced iron matrix composite

ZTA particle modified by Ti–Ni powder(Ti–Ni@ZTAp) reinforced iron matrix composite (Ti–Ni@ZTAp-VCp/Fe45) was fabricated by powder metallurgy. The microstructure, scratch properties and formation mechanism of the interface were investigated. An interface layer of 10 μm–20 μm was formed between ZTAp and VCp/Fe45 matrix, which reduced the defects at the interface and played a good transition role. The phases in the interface layer were TiO, Ti6O11 and ZrO2. Metallized layer was formed on the surface of ZTAp after the vacuum sintering of Ti–Ni powder modified ZTAp at 1500 °C. Elemental diffusion occurred between the Ti–Ni powder and ZTAp, which resulted that the ZrO2 phase migrated from ZTAp to the coating layer and reacted with the Ti–Ni powder to form new phases of Ni3Ti, TiO and Ti6O11. The models of the formation mechanisms of the metallized layer, interface layer between ZTAp and VCp/Fe45 matrix were established. Ni3Ti in the metallized layer on the surface of ZTAp was further decomposed duing the vacuum sintering of Ti–Ni@ZTAp-VCp/Fe45 composite, and then the elements Ni and Ti diffused with elements Fe, Cr and V of the VCp/Fe45 matrix. The V element diffusing to the interface layer can further displaced the Ti element in ZTAp and realized the diffusion from iron matrix to ZTAp. The metallized layer on the surface of ZTAp was transformed into an interface layer between ZTAp and VCp/Fe45.

Insight into the cracking mechanism of super-elastic NiTi alloy fabricated by laser powder bed fusion

ABSTRACT Laser powder bed fusion is considered to be an effective method for forming high-precision NiTi alloys. NiTi alloys formed from Ti-rich or low-Ni content NiTi powders as raw materials exhibit shape memory or trained to be superelastic at room temperature. To fabricate super-elastic NiTi alloys without training, it is often to increase the Ni content of the powder. However, Ni-rich NiTi powders are highly susceptible to cracking during fabrication. Therefore, this study has conducted a systematic investigation and proposed a corresponding process optimisation strategy. The results show that cracking is the result of the combined effect from residual thermal stresses and microstructure during the printing process. The melt pool morphology influenced by the thermal history as well as elemental evaporation determines the direction of crack formation and propagation. We have successfully fabricated room-temperature super-elastic NiTi samples without cracking using high laser power and high scanning speed.

Active interlocking metasurfaces enabled by shape memory alloys

Interlocking metasurfaces (ILMs) are a newly developed joining technology that relies on arrays of interlocking features that transmit force and constrain motion between adjoining bodies in one or more directions. This study explores harnessing the shape memory effect (SME) in Nickel-Titanium shape memory alloys (NiTi SMAs) in structures fabricated using additive manufacturing (AM) to advance the development of active ILMs by creating unit cells that open or close at specific temperatures. The study encompasses designing and fabricating two distinct interlocking array configurations using near-equiatomic NiTi powder and the laser powder bed fusion (L-PBF) AM technique, following a previously developed AM process optimization framework to manufacture defect-free parts. To guide the design process, finite element analysis (FEA) was employed to predict strain values during engage-disengage cycles. The martensitic transformation characteristics of the ILMs were characterized. Thermomechanical testing revealed that the ILMs demonstrate high locking force once engaged, coupled with complete shape recovery and good cyclic stability. Digital image correlation (DIC) was also employed to validate the FEA predictions during the engage-disengage cycles. The results indicate that NiTi SMA-based ILMs can be designed and fabricated into complex shapes using L-PBF. By leveraging the SME, the functionality of an ILM can be improved upon. The combination of computational modeling, additive manufacturing, and thermomechanical and physical property characterization provides a framework for designing future ILMs out of active materials.

Design and additive manufacturing of bionic hybrid structure inspired by cuttlebone to achieve superior mechanical properties and shape memory function

Lightweight porous materials with high load-bearing, damage tolerance and energy absorption (EA) as well as intelligence of shape recovery after material deformation are beneficial and critical for many applications, e.g. aerospace, automobiles, electronics, etc. Cuttlebone produced in the cuttlefish has evolved vertical walls with the optimal corrugation gradient, enabling stress homogenization, significant load bearing, and damage tolerance to protect the organism from high external pressures in the deep sea. This work illustrated that the complex hybrid wave shape in cuttlebone walls, becoming more tortuous from bottom to top, creates a lightweight, load-bearing structure with progressive failure. By mimicking the cuttlebone, a novel bionic hybrid structure (BHS) was proposed, and as a comparison, a regular corrugated structure and a straight wall structure were designed. Three types of designed structures have been successfully manufactured by laser powder bed fusion (LPBF) with NiTi powder. The LPBF-processed BHS exhibited a total porosity of 0.042% and a good dimensional accuracy with a peak deviation of 17.4 μm. Microstructural analysis indicated that the LPBF-processed BHS had a strong (001) crystallographic orientation and an average size of 9.85 μm. Mechanical analysis revealed the LPBF-processed BHS could withstand over 25 000 times its weight without significant deformation and had the highest specific EA value (5.32 J·g−1) due to the absence of stress concentration and progressive wall failure during compression. Cyclic compression testing showed that LPBF-processed BHS possessed superior viscoelastic and elasticity energy dissipation capacity. Importantly, the uniform reversible phase transition from martensite to austenite in the walls enables the structure to largely recover its pre-deformation shape when heated (over 99% recovery rate). These design strategies can serve as valuable references for the development of intelligent components that possess high mechanical efficiency and shape memory capabilities.

Effects of the Addition of Tin Powder to Perovskite Precursor Solutions on Band Bending at PEDOT:PSS/Perovskite Interfaces in Mixed-Cation Mixed-Halide Tin Perovskite Solar Cells.

Using electron spin resonance (ESR) spectroscopy, we investigated the effects of the addition of tin (Sn) powder to perovskite layers on band bending at the perovskite surface near poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) hole-transport layers in perovskite solar cells (PSCs) involving formamidinium (FA)-methylammonium (MA)-mixed-cation I-Br-mixed-halide tin perovskites. We performed dark ESR spectroscopy measurements of a PEDOT:PSS/FA0.75MA0.25Sn(I0.75Br0.25)3 stack and of a PEDOT:PSS/Sn-powder-added FA0.75MA0.25Sn(I0.75Br0.25)3 stack. The results indicate that FA0.75MA0.25Sn(I0.75Br0.25)3 layers have significant downward band bending near PEDOT:PSS layers. Such downward band bending is unfavorable for hole selectivity and surface passivation at the interface. However, the addition of Sn powder to the tin perovskite precursor solution was found to significantly prevent the downward band bending and rather cause upward band bending, which can improve the hole selectivity and field-effect passivation quality. This can be due to prevented oxidation of perovskite layers by Sn powder addition. These findings are crucial for developing highly efficient and stable tin perovskite solar cells.

Influence of Laser Energy on the Structural and Optical Properties of Sn Nanoparticles produced with Laser-Induced Plasma

This study aimed to investigate the structure and optical properties of Sn nanostructures. Thin tin (Sn) films were deposited on glass substrates using the pulsed laser deposition method. Nd:YAG laser with fundamental wavelengths of 532 nm and 1064 nm was used to create Sn nanostructures with varying energies of 400 mJ to 700 mJ and the same frequency of 6 Hz. The tin powder was compressed into a disc with a one-centimetre diameter to serve as a sample. The X-ray diffraction (XRD) pattern showed a crystalline structure with several Sn nanostructures peaks at various energies (400–700 mJ). The results revealed a crystalline size of 65.90 nm and 86.55 nm at 700 mJ, while the size was 40.19 nm and 17.19 at 400 mJ for the given wavelengths (532nm and 1064 nm), respectively. The appearance of Sn nanostructures and the aggregation of, particularly in the form of cauliflower, were revealed in Field emission scanning electron microscopy (FE-SEM) images. The results of the dispersive energy X-ray spectroscopy (EDS) analysis showed that various amounts of tin, carbon, and oxygen were present. Additionally, the optical characteristics were investigated of each film using absorbance spectra, which covered a range of wavelengths from 190 to 1100 nm. As the laser power increased, the band gap energy values in the optical properties decreased, falling into the ranges of 3.06 to 1.65 eV and 3.22 to 1.82 eV at 1064nm and 532nm, respectively.

3D printing of shape memory Alloys for complex architectures of smart structures

Shape Memory Alloys (SMA) are materials used to design smart structures with intrinsic functional properties and improved efficiency. This is a key aspect of aerospace industry and makes SMA good candidates in this field. One of the most widespread SMA is the equiatomic NiTi alloy which, however, has the strong limitation of poor machinability, so only simple shapes can be obtained. Additive Manufacturing processes allow to overcome this limit and to design complex shapes. Compared to other metallic materials, the optimization of the process for NiTi alloy is complicated because, beside mechanical properties and presence of defects, considerable attention needs to be dedicated to the material functionality. The high temperatures involved in the additive process significantly affect the material properties due to possible evaporation of Ni and formation of precipitates that enable a shift of the phase transformation temperatures. This paper is focused on the optimization of the process parameters of the NiTi alloy printed through the Laser Powder Bed Fusion (L-PBF) to ensure optimal pseudo-elastic behaviour, which is essential for the design of structural dampers. This was accomplished starting from simple structures and then designing a damper that couples the pseudoelasticity of NiTi with load support capacity.The L-PBF is a powder-bed technique that selectively melts layers of micrometric metal powder. A pseudoelastic NiTi powder with 50.8 at. % of Ni content was selected and characterized through scanning electron microscope (SEM) and observations connected to an Energy Dispersive X-ray Spectroscopy (EDX) probe. After that, some cubic samples were manufactured, with the dimension of 3 × 3 × 15 mm3. A set of different laser powers and scanning speeds were used to find the set of process parameters that optimize the functional properties of the printed parts. Near fully dense specimens with density higher than 99.5 % were selected for further investigations. Differential scanning calorimetry (DSC) and mechanical tests were performed on as-built and heat-treated samples.Quasi-static mechanical tests were accomplished in compression mode, at different strains, up to 8 %. It was observed that the residual strain for cyclic loading at 4 % is lower than 1 %, so good recovery of the deformation was shown. Moreover, numerical analyses that mimic the pseudoelastic behaviour in compression tests were implemented.Finally, the best set of parameters was selected on the basis of the material's ability to recover deformations and its loss factor.

Wear performance of Ti-based alloy coatings on 316L SS fabricated with the sputtering method: Relevance to biomedical implants.

This investigation was conducted to encapsulate 316L SS with a Ti-based alloy coating. The aim was to fabricate a coating using TiN, TiO2, and TiCoCr powders on 316L SS through the physical vapor deposition (PVD) sputtering process. The powders were consecutively coated on 316L SS through the PVD sputtering process with coating durations of 30, 60, and 90 min. Further microhardness, surface roughness, microabrasion, and adhesion strength tests were also carried out. A 60% improvement in abrasion resistance was observed in TiCoCr-coated samples compared to the uncoated substrate. The X-ray diffraction results confirmed the optimal formation of Ti alloy coatings with corresponding orientation over the SS substrates. Moreover, TiCoCr with a 90 min coating duration had much better surface characteristics than TiO2 and TiN. The 90 min coating duration should be optimal for coating in steel for bio-implants.

Microstructural and mechanical properties of microwave sintered bulk titanium nitride nanoceramics

In the present work nano-sized TiN powders were consolidated and sintered in nitrogen, argon and air using microwave power of 900 W at frequency 2.45 GHz. Green compacts were exposed to microwave energy, and heated at an in-situ temperature of 1500 °C without holding time. The relative density achieved was ∼92 %. X-ray diffraction analysis showed presence of TiN as the dominant major phase. The microstructures indicate that the sintered samples retained their nanocrystallinty, though aggregates comprising clusters of nanoparticle was noticed with size in the range of 80–400 nm due to high heating rate. Micro indentation assessment indicates average Vickers hardness of 15.2 ± 0.5 GPa. The lengths of cracks originating from the indentation edges were measured; the indentation fracture toughness were obtained between 4.0 and 4.5 MPa.m1/2. The observed properties indicate the suitability of the sintered material in tribological applications.

In Situ Generation of TiCN Ni‐Based Coatings by Laser Cladding and Study of Their Structure and Properties

The influence of the ratio of TiN powder, graphite powder, and Ni60 powder on the phase composition, microstructure, microhardness, and wear properties of the TiCN Ni‐based coating on H13 steel is investigated. The findings indicate that varying proportions of TiN powder, C powder, and Ni60 powder have a minimal impact on the coating's phase composition. The diffraction peak intensity of TiC0.3N0.7 increases with the addition of (C + TiN) in the blended powder, while the crystallinity of TiC0.3N0.7 in the Ni‐based coating with a 30% (C + TiN) mass fraction decreases. The grain structure of the 20% Ni‐based coating is fine and uniform, while the microstructure of the 30% Ni‐based coating is characterized by a large polymerization phase‐containing Ti elements, with the TiCN‐reinforced phase exhibiting irregular grain morphology. The microhardness HV0.5 of the coating with a 20% (C + TiN) mass fraction ranges from 725 to 772, with an average hardness of 747.8 HV0.5, which is 3.4 times the hardness of the substrate material and 1.3 times the hardness of the Ni‐based coating. As the mass fraction of (C + TiN) in the hybrid powder increases, the friction loss mass of the coating tends to decrease and then increase. The average wear of the Ni‐based coating with a 20% (C + TiN) mass fraction is ≈22.4% of that of the substrate and 50% of that of the Ni‐based coating, demonstrating excellent wear resistance. The wear mechanism is primarily characterized by brittle spalling and abrasive wear.

Study of the biocompatibility of porous 3D-TiNi implants in vivo

Introduction. Porous TiNi alloys are widely used in medicine as osteoreplacement implants due to their unique properties of superelasticity and biocompatibility, but their clinical use is severely limited by time-consuming manual fabrication and the inability to create precise geometries. Reconstructive surgery for the replacement of bone defects requires biocompatible endoprostheses of individual shape and complex geometry. The use of porous 3D-TiNi implants can be a solution to many problems in traumatology and bone oncology.Aim: To evaluate the possibility of using porous 3D-TiNi implants in osteoplastic surgery based on a study of the structure and biocompatibility of the material under in vivo conditions.Material and Methods. Porous samples in the form of cones and a single implant for maxillofacial surgery were prepared from TiNi powder by selective laser melting. To print an individual implant for maxillofacial surgery, the personal data of the patient at the Oncology Research Institute were used. The macrostructure, elemental and phase composition of porous titanium nickelide samples were investigated using scanning microscopy and X-ray diffraction analysis. The biocompatibility of porous cone-shaped samples was evaluated in vivo using guinea pigs whose condition was analysed by CT scanning.Results. Structural studies of porous titanium nickelide samples showed that selective laser melting can be used to obtain a continuous porous structure with strong contact bridges between particles of a three-phase powder. In vivo testing of the cone-shaped implants showed no local inflammatory changes, rejection or deformation of the hind limb axes of the experimental animals. The basic feasibility of fabricating a custom implant of complex geometry from TiNi powder using selective laser melting according to a patient’s MSCT data was demonstrated.Conclusions. Porous 3D-TiNi implants obtained by selective laser melting showed high biocompatibility under in vivo conditions. An experimental study confirmed the efficacy and ease of use of 3D TiNi implants, their excellent self-fixation in bone tissue, and bone tissue augmentation at the interface with the implant. The macrostructure, chemical and phase composition of the implant material was found to be close to traditional porous TiNi alloys. It was shown that the method of selective laser melting makes it possible to create complex geometric defects in bone tissue from TiNi.

A Systematic Approach to Optimize Parameters in Manufacturing Complex Lattice Structures of NiTi Using Electron Beam Powder Bed Fusion Process

Herein, the quality and accuracy to manufacture delicate parts from NiTi powder using electron beam powder bed fusion (EB‐PBF) technology is investigated. Therefore, benchmarks with thin cylinders and thin walls are designed and fabricated using two distinct scan strategies of EB‐PBF manufacturing (i.e., continuous melting and spot melting) with different process parameter sets. After these optimizations, four different lattice structures (i.e., octahedron, cell gyroid, sheet gyroid, and channel) are manufactured and characterized. It is shown both continuous melting and spot melting modes are able to manufacture lattices with relative densities over 97%. And as‐built lattice structures exhibit an excellent pseudoelasticity up to 8% depending on the design of the structure, e.g., the channel structure shows more deformation recoverability than the cell gyroid. This is attributed to the integrity of geometry as well as compressive mode of the mechanical loading. Of course, the compressive strength and ultimate compressive strength also increase with the increasing volume fraction. Moreover, the spot melting can be used as an engineering tool to customize a delicate beam‐shaped structure with a superior pseudoelasticity.

Porosity and phase composition effects on SHS-NiTi structure and mechanical properties

NiTi samples with 59–70% porosity were obtained by the self-propagating high-temperature synthesis (SHS) using Ti, Ni, and NiTi powders as inert. The maximum and average pore sizes increase, while the maximum and average dimensions of the bridges decrease with porosity, controlled by adjusting the amount of inert additives, based on the surface and cross-sectional microscopy studies. The phase composition of porous NiTi was determined by X-ray diffraction. The alloy contains an austenitic B2 TiNi phase, a martensitic B19′ TiNi phase, and a secondary Ti2Ni phase. SHS-NiTi samples with different porosity were tested by uniaxial compression, revealing mechanical properties’ dependence on porosity. It is shown that with an 11% increase in the NiTi alloy porosity, the yield and compressive strength are reduced by almost a factor of 2.

Thermal plasma spraying of NiTi powder for thick coating of shape memory alloy

In this article, NiTi coating was fabricated via a thermal plasma process by tuning various parameters. The work aims to achieve shape memory behavior that could retained in the plasma-sprayed samples. Various plasma spraying process parameters such as plasma power, powder feed rate, spraying plan, and net powder spray were taken into consideration for the spraying. Microstructural, thermal, mechanical, and shape memory behavior was analyzed on the plasma-sprayed samples. Various phases austenite, martensite, and intermetallic phases such as NixTiy, Ni-Ti-O, Ni, and Ti were confirmed from the X-ray diffraction analysis. The presence of these phases in the samples contributes to the thermal transformation and mechanical behavior. A less heat-affected zone of 10 µm along the interface was confirmed without any diffusion of elements from the substrate to the coating layers. There was a homogenous distribution elemental composition of Ni and Ti throughout the coating layers. The shape memory behavior of the coating samples was confirmed by the thermo-mechanical analysis by performing the response in multiple cycles.

Effects of gas pressure and catheter length on the breakup of discontinuous NiTi droplets in electrode induction melting gas atomization

NiTi powders used for selective laser melting have here been fabricated by the breakup of discontinuous droplets in electrode induction melting gas atomization (EIGA). The morphology, particle size distribution, and hollow ratio of the powder were characterized by scanning electron microscopy (SEM), laser particle size analyzer, and computed tomography (CT), respectively. The effects of gas pressure and catheter length on the particle size distribution and powder morphology were then studied. Furthermore, the effects of the classifier wheel speed on the particle size distribution and yield of the 15–53 μm powder in the classification process were also analyzed. The results showed that the average particle size (D50) of the NiTi powder first decreased and, thereafter, increased as the atomization gas pressure increased. This was also the situation with catheter length. Also, the yield of the 15–53 μm powder increased with an increase in the classifier wheel speed. The optimum parameters were a gas atomization pressure of 5 MPa, a tension length of 28 mm, and a classifier wheel speed of 660 r min−1. For this optimized condition, the D50 value and the yield of the NiTi powder were 57.54 μm and 46.4%. In addition, the flowability, hollow ratio, and oxygen content were 15.8 s/50 g, 0.31%, and 450 ppm, respectively.

Analysis of the Particle Size and Morphology of Tin Powder Synthesized by the Electrolytic Method.

This article discusses the effect of electrolysis parameters on the particle size and morphology of the tin powder synthesized by the electrolytic method. The electrolytic method is simple and can eliminate the risk of lead and arsenic gas emissions owing to the low temperature of the process. The effects of tin concentration in a sulfate-based electrolyte, a mass ratio of thiourea/gelatin as additives, current density, and electrolysis time on the particle size and morphology of the synthesized tin powder were examined. Pure tin and titanium plates were used as the anode and the cathode, respectively. After the electrolysis experiments were completed, the synthesized tin powders were analyzed by a particle size analyzer, a scanning electron microscope, and X-ray diffraction. The optimum condition of the experiment that resulted in the highest D90 was achieved at an initial concentration of SnSO4 = 3 g/L, a mass ratio of thiourea/gelatin = 1/4, a current density of 1 A/dm2, and a 10 min electrolysis time. Under this condition, 90% of the tin powder size obtained was smaller than 2.279 μm, showing a rounded morphology with a length-to-width ratio of 1.15. The current efficiency increased with increasing tin concentration, decreasing current density, and a shorter electrolysis time.

Study on lap joining and characterization of tin (Sn) powder on stainless steel SS304 using microwave heating

AbstractMetal bonding via joints of low melting point materials such as zinc and tin has been technically challenging. This paper presents a unique technique for bonding small dimensions and the low melting point of materials through the microwave hybrid heating (MHH) process. Joint of stainless steel SS304 was applied to the joint with the tin (Sn) powder with the application of microwave radiation by using domestic microwave oven at 2.45 GHz of constant frequency, 200–360 W of microwave power, 120–180 s of exposure time, and 10–20 % of the epoxy rate. A developed heat chamber was used as a susceptor and insulator in the microwave hybrid heating (MHH) process. The tin powder and parent metals were strongly bonded as lap position by the microwave hybrid heating (MHH) process at 360 W of microwave power, 180 s of constant exposure time, and 20 % of the constant epoxy rate. Characterization of the joint was evaluated through microhardness and x‐ray diffraction (XRD) analysis techniques. It was found that the intermetallic compounds (phase) of nickel tin (NiSn), iron tin (Fe1.84Sn), sulfur tin (SSn), chromium tin (Cr2Sn3), chromium tin (CrSn2), and tin phosphorus (SnP) at the joint surface with highest microhardness obtained at 498.4 HV 0.05 at 360 W of microwave power.

Microstructure, mechanical properties and wear behaviors of TiN/Ti composite coating on laser surface textured Ti6Al4V alloy fabricated by MHz picosecond laser surface alloying

Ceramic-reinforced metal matrix composites (MMCs) coating fabricated by laser surface melting effectively improves the surface mechanical and wear properties of titanium alloys. However, power of several hundred watts is generally used in traditional laser processing, which introduces excessive heat input and leads to thermal deformation and thermal effects, resulting in cracks and reducing mechanical properties and service life of coatings. In order to improve the microhardness and anti-wear properties of Ti6Al4V alloy and extend the service life, a picosecond laser (ps-laser) with a power of 23 W and repetition rate of 19 MHz was utilized to fabricate the uniform and crack-free MMCs coating (TiN/Ti) by melting TiN powders on the textured Ti6Al4V surface. Three different textures with different texture densities and depths were used to evaluate their effects on coatings. Results showed that the reinforced TiN phase was in the form of fine dendrites with an average secondary dendrite arm spacing of 0.84 µm. The microhardness and the anti-wear properties were both inversely proportional to the texture densities because of controlling the volume fraction of TiN in the coating. The microhardness of the sample with greatest microhardness increase was significantly improved from 355 HV0.5 (base material) to 1000 HV0.5 due to the addition of the TiN phase. The sample with a texture density of 5% showed the best anti-wear properties (about 22 times that of the substrate) due to the effective suppression of three-body abrasive wear.

Experimental investigation on selective laser melting additive manufacturing of non-ferromagnetic heterogeneous material based on TiNi alloy with Ta coating

In order to manufacture non-ferromagnetic heterogeneous material by Selective Laser Melting (SLM), it is necessary to solve the separation problem of non-ferromagnetic mixed powders after SLM forming. This research presents how to resolve this problem using TiNi/Ta mixed powders by ultrasonic vibration screening method and the analysis of SLM manufacturing experiment for non-ferromagnetic heterogeneous material. The purity of TiNi and Ta powders after separation could reach 99.7087%wt% and 98.8501wt% respectively, which both reached a relatively high purity. A TiNi alloy sample with Ta coating and TiNi/Ta gradient transition was manufactured successfully by SLM. The material interface of the sample achieves metallurgical bonding, and the color of the sample profile shows a gradient transition. The EDS analysis shows that the material composition changes from Ta ->Ta/TiNi gradient ->TiNi from surface to inside of the sample. The Ta coating contains over 92.5wt% Ta, and the TiNi matrix contains over 98.69wt% TiNi. Along the powder laying direction, it is difficult to clean the small powder near the solid-powder or solid-solid interfaces made of two different materials, which causes micro polluted areas near the interfaces. This study also provides a new method for integrated manufacturing of TiNi alloy part with Ta coating.