Solid-state Diffusion Research Articles

Dynamic Elucidation of Lithium Insertion Reaction into MgMn2O4 Spinel

Since the expansion of Li-ion battery applications from portable electronic devices to electric vehicles and renewable energy storage, high-power capability is becoming increasingly important as a battery performance metric. Elucidation of the reaction mechanism of Li insertion materials is a major task in the battery research field, because it offers crucial insights into both the kinetics of the Li insertion reaction and the development of high-power Li-ion batteries. In this study, the mechanism for Li insertion into MgMn2O4 spinel, across the entire reaction range, was elucidated by fitting the current response during constant-potential discharge reaction using solid-state kinetic reaction (nucleation-growth, diffusion, and contraction) models. The fitting results revealed that the Li insertion reaction in the dynamic (non-equilibrium) process proceeds via nucleation-growth followed by solid-state Li-ion diffusion (single-phase), while Li insertion into MgMn2O4 proceeds through a two-phase coexistence reaction in the equilibrium state, as observed by ex situ XRD analysis. The finding that the reaction mechanisms in the dynamic and equilibrium processes are different indicates that the kinetics of the Li insertion reaction should be considered through a dynamic rather than an equilibrium process viewpoint.

Melt Synthesis of Lithium Manganese Iron Phosphate: Part I. Composition, Physical Properties, Structural Analysis, and Charge/Discharge Cycling

Melt synthesis is a fast and simple process to make dense LiMnyFe1-yPO4 (LMFP with 0 ≤ y ≤ 1) from all-dry, low-cost precursors with zero waste. This study characterizes melt LMFP materials with 0%–100% Mn after particle size reduction by planetary milling and carbon coating with glucose. The melt LMFP samples show higher electrical conductivity at similar pellet density than LFP (0% Mn) and LMFP (79% Mn) reference samples made by traditional methods. The melt LMFP samples exhibit higher crystallinity than the reference samples and show no crystalline impurities. Their unit cell volume and crystallographic density scale with Mn content; the percentage of Fe and/or Mn in Li positions is below 1.5%, which is comparable to reference samples. Crystallite sizes of at least 100 to 175 nm are observed for melt LMFP, which is larger than the fine ∼50 nm crystallites of reference LMFP. Melt LFP shows specific discharge capacity and cycling stability comparable to reference LFP, but the melt LMFP samples with 25%–100% Mn shows worse performance than reference LMFP (79% Mn). Part two of this study will quantify the solid-state lithium diffusion coefficient in melt LMFP materials and correlate it to their electrochemical performance.

Atomistic Assessment of Melting Point Depression and Enhanced Interfacial Diffusion of Cu in Confinement with AlN.

The continuing trend in heterogeneous integration (i.e., miniaturization and diversification of devices and components) requires a fundamental understanding of the phase stability and diffusivity of nanoconfined metals in functional nanoarchitectures, such as nanomultilayers (NMLs). Nanoconfinement effects, such as interfacial melting and anomalous fast interfacial diffusion, offer promising engineering tools to enhance the reaction kinetics at low temperatures for targeted applications in the fields of joining, solid-state batteries, and low-temperature sintering technologies. In the present study, the phase stability and atomic mobility of confined metals in Cu/AlN NMLs were investigated by molecular dynamics, with the interatomic potential compared to the ab initio calculations of the Cu/AlN interface adhesion energy. Simulations of the structural evolution of Cu/AlN nanomultilayers upon heating in dependence on the Cu nanolayer thickness demonstrate the occurrence of interfacial premelting, a melting point depression, as well as extraordinary fast solid-state diffusion of confined Cu atoms along the defective heterogeneous interfaces. The model predictions rationalize recent experimental observations of premelting and anomalous fast interface diffusion of nanoconfined metals in nanostructured Cu/AlN brazing fillers at strikingly low temperatures.

Multiscale coupling of surface temperature with solid diffusion in large lithium-ion pouch cells

Untangling the relationship between reactions, mass transfer, and temperature within lithium-ion batteries enables approaches to mitigate thermal hot spots and slow degradation. Here, we develop an efficient physics-based three-dimensional model to simulate lock-in thermography experiments, which synchronously record the applied current, cell voltage, and surface-temperature distribution from commercial lithium iron phosphate pouch cells. We extend an earlier streamlined model based on the popular Doyle–Fuller–Newman theory, augmented by a local heat balance. The experimental data reveal significant in-plane temperature non-uniformity during battery charging and discharging, which we rationalize with a multiscale coupling between heat flow and solid-state diffusion, in particular microscopic lithium intercalation within the electrodes. Simulations are exploited to quantify properties, which we validate against a fast full-discharge experiment. Our work suggests the possibility that non-uniform thermal states could offer a window into—and a diagnostic tool for—the microscopic processes underlying battery performance and cycle life.

Experimental diffusion research and assessment of diffusional mobility in HCP Mg–Al-Ga ternary alloys

It is in this work that the diffusion behavior in HCP Mg–Ga binary alloys at temperatures from 673 K to 873 K and in Mg–Al-Ga ternary alloys in 673–723 K was investigated by the solid-state diffusion couple experiments. The inter- and impurity diffusion coefficients were then extracted from the composition profiles acquired by electron probe microanalysis (EPMA) via the Sauer-Freise, Whittle-Green and Hall methods, respectively. The extracted impurity diffusion coefficient of Ga in pure HCP-Mg follows an Arrhenius relation with the pre-exponential factor D0 = 1.4 × 10−5 m2/s and activation energy Q = 116869 J/mol. The interdiffusion coefficients of the Mg–Ga binary alloys were found to increase with increasing the Ga content. Whereas in the Mg–Al-Ga ternary, the average main interdiffusion coefficients D˜GaGaMg within the investigated composition space is 5.4 times larger than that of D˜AlAlMg at 673 K and 4.6 times at 723 K, respectively, revealing that Ga is a much faster diffuser than Al in the ternary alloys. The main interdiffusion coefficients D˜GaGaMg and D˜AlAlMg, as well as the impurity diffusion coefficients DAl(Mg−Ga)∗ and DGa(Mg−Al)∗ exhibit increasing composition trends as the content of diffusing species increases, either Al or Ga. Close inspection suggests that Ga has significant effect on the diffusion of Al while the Al effect is minor on Ga. The diffusion coefficients extracted in this work, together with other selected diffusion data in literature, were critically evaluated to assess the diffusional mobility for the HCP Mg–Al-Ga ternary alloys. The optimized parameters of diffusional mobilities enable such diffusion behaviors as composition profiles and diffusion paths to be well represented and then predicted, in most cases, consistent with the experimental findings and therefore validating the mobility parameters assessed in this work.

The crack initiation and strengthening mechanism in FGH96 solid-state diffusion bonding joint by quasi-in-situ SEM-DIC and EBSD

The crack initiation and strengthening mechanism of the FGH96 solid-state diffusion bonding joint at room temperature and 50 °C were investigated based on the interaction between microscopic strain concentration and microstructure features. Digital image correlation using SEM images (SEM-DIC) and electron backscattering diffraction (EBSD) technologies were applied. The results showed that the carbides, twin boundaries (TBs) combined with the grain orientation, and the high-angle grain boundaries (HAGBs) played a critical role in the crack initiations. At room temperature, the cracks initiated at the carbide/matrix interface due to the strain mismatch. Besides, the newly formed low-angle grain boundaries (LAGBs) or HAGBs in the grain interior, which were attributed to the direct or indirect inhibition (by forming the stress-affected regions) effect on the slip movements from TBs combined with grain orientation, were developed into cracks with deformation increasing. Moreover, some grain junctions with twin grains participation were also the crack origins due to the strain compatibility and adhesive failure. The cracks at different positions propagated and coalesced to lead to the intragranular fracture. At 650 °C, the effects of carbides, TBs, and grain orientation on the strain accumulation were weakened and contributed little to the crack initiation. The microscopic strain mainly accumulated along HAGBs, leading to the cracks originating along the HAGBs and the intergranular fracture. Due to the different deformation mechanisms, the relative tensile strength and elongation of the joint reached more than 90% at room temperature, while 79.36% and merely 24.4%, respectively, at 650 °C.

Correlation governs the impurity (Ti, Zr, Hf) diffusion in face−centered cubic iridium through first−principles calculation

Solid state diffusion depends on many factors, including crystal structure, vacancy concentration, energy barrier, jump frequency, correlation, etc.. In this work, those factors were systematically investigated for dilute IVB transition metals X (X = Ti, Zr, Hf) diffusion in face−centered cubic (FCC) Ir using first−principles calculations together with quasi−harmonic thermodynamics, climb−image nudged elastic band (CINEB), and five−frequency diffusion model. The results show that correlation which is often neglected in low melting point metals and alloys plays a key role in the impurity diffusion in Ir. The correlation factor which ranges from 10−13 at 500 K to 10−1 at 2000 K overturns the contributions from other factors, like vacancy concentration, energy barrier, and jump frequency. The diffusion coefficient of Ir−X (X = Ti, Zr, Hf) systems follows DHf > DZr > DTi, different from our traditional knowledge. Our findings not only give a good recount to the counterintuitive experimental phenomena in Ir oxidation resistance coating or ultrahigh−temperature Ir-based superalloys, but also provide valuable diffusion data for rational design of Ir-based materials for applications with harsh environment.

Cation and anion (de)intercalation into MXene/Perovskite oxides for high-rate intercalation pseudocapacitance

Intercalation pseudocapacitance is the next hope for electrochemical energy storage devices to offer high energy density without sacrificing power density. Under intercalation pseudocapacitance, ions (e.g. Li+ into T-Nb2O5, but not limited to cation intercalation only) intercalate into the host materials without phase conversions and no limitations from solid-state diffusion, unlike batteries. Here, a concept of both cations and anions (de)intercalation into the hybrid electrode comprising nanocomposite (MLMO) of MXene (Ti3C2Tx) and perovskite oxides (LaMnO3-δ, LMO) are demonstrated. Independently, multilayered MXene and oxygen deficient LMO show cation and anion-based intercalation pseudocapacitance, respectively. During analyzing the electrochemical process through ex situ XPS, it is observed that not only K+ ions but OH− ions also (via formation of O2−) (de)intercalate into MLMO and contribute to the total charge storage. Accordingly, MLMO exhibits high capacitance retention (70.82%) even at a high current density of 30 A g−1 (313.6 F g−1). Next, a fast-kinetics dual-ion intercalated pseudocapacitive symmetric device with 1.6 V is fabricated which shows a high energy density of 34.1 Wh kg−1 and astonishing power density of 14.51 kW kg−1. This study sheds light on new dual-ion intercalation chemistry and sets a concrete path for the establishment of high energy storage devices with fast-kinetics.

Constructing Hydrophobic Interface with Close-Packed Coordination Supramolecular Network for Long-Cycling and Dendrite-Free Zn-Metal Batteries.

Commercialization of aqueous zinc-metal batteries remains unrealistic due to the substantial dendrite growth and side reaction issues on the zinc anodes. It is highly demanded to develop easy-to-handle approaches for constructing stable, dense, as well as homogeneous solid anode/electrolyte interfaces. Herein, the authors construct the zinc anode interface with a close-packed Zn-TSA (TSA = thiosalicylate) coordination supramolecular network through the facile and up-scalable wet-chemical method. The hydrophobic Zn-TSA network can block solvated water and establish a solid-state diffusion barrier to well-distribute the interfacial Zn2+ , thus inhibiting hydrogen evolution and zinc dendrite growth on the anode. Meanwhile, the Zn-TSA network induces the formation of a uniform and stable solid electrolyte interphase composed of multiple inorganic-organic compounds. This denser structure can accommodate and self-heal the crack/degradation of the anode interphase associated with the repeated volume changes, and suppress the generation of detrimental by-product, Znx (OTF- )y (OH)2x-y ·nH2 O. Such a rationally fabricated anode/electrolyte interface further endows the assembled symmetric cells with superior plating/stripping stability for over 2000 h without dendrite formation (at 1mA cm-2 and 1 mAh cm-2 ). Furthermore, this zinc anode has practical application in the Zn-MoS2 and Zn-V2 O5 full cells. This study provides a new train of thought for constructing the dense interface of zinc-metal anode.

Surface modification of pure aluminum via Ar ion bombardment for Al/Al solid-state diffusion bonding

Ar ion bombardment was applied to modify the aluminum surface and a subsequent solid-state diffusion bonding was performed. The effect of Ar ion bombardment on surface conditions and properties was studied to analyze the relationship between surface modification and joint performance. With increase of the Ar ion energy, the surface oxide film was removed and its surface roughness tended to decreased first and then increased. The oxide-free aluminum surface with minimal roughness of 0.61 nm was obtained by 1 keV bombardment while the numerous small dislocation loops uniformly distributed in the aluminum surface structure enhanced the surface hardness. Under high-energy bombardment (>5 keV), the surface became swollen or even porous due to the growth of dislocation loops and Ar bubbles that made the surface rough and embrittled, which deteriorated the microstructure and strength of bonded joints. The well-bonded joint with shear strength of 45.9 MPa was obtained at 1 keV bombardment and diffusion bonding temperature of 450 °C. The specific shear strength of ~60% was higher than that of conventional Al diffusion bonded joints. This work is of significance for the manufacture of well-bonded aluminum microchannel heat exchangers. • Bombardment-induced modification is studied in terms of morphology and structure. • The relationship among bombardment, modification and bonding behavior is discussed. • The evolution of bombarded defects affects the surface hardening and embrittlement. • Well-bonded Al joints are obtained at low temperatures by Ar ion bombardment.

Influence of pulsed direct current on the growth rate of intermetallic phases in the Ni–Al system during reactive spark plasma sintering

The effect of pulsed direct current (PDC) on solid-state diffusion in the Ni–Al binary system was investigated. Two experimental schemes were employed: in the presence and absence of an electric field. The diffusion couples were heat-treated for 1.5, 3, and 5 h at 803, 833, and 863 K. Under the investigated conditions, only two intermetallic phases (NiAl3 and Ni2Al3) formed at the boundary of the metals. It was shown that the PDC passing through the diffusion couple significantly enhanced the growth rates of both phases. The apparent reaction–diffusion coefficients were DNiAl3=4.0×10−9exp(−7.6×104RT) and DNi2Al3=9.7×10−9exp(−8.4×104RT) in the field-assisted scheme, whereas their corresponding values in the field-insulated scheme were DNiAl3=6.1×10−5exp(−1.55×105RT) and DNi2Al3=3.7×10−4exp(−1.71×105RT). The results directly imply that the effective activation energy of diffusion decreases by approximately two times when the PDC passes through the media.

Low-Temperature Reactive Sintered Porous Mg-Al-Zn Alloy Foams

By using carbamide granules as the space holder, Mg alloy foams with interconnected pore structures were synthesized by reactive sintering of a mixture of Mg, Al and Zn powders. The effect of Zn/Al on the microstructural evolution and compressive strength of porous Mg-9Al-xZn (x = 1, 5) alloy foams was investigated. The phase diagram simulation approach was used to determine the sintering temperature. The analysis results show that the formation of binary secondary phases or intermetallic compounds is a crucial factor in achieving bonding strength for the porous Mg alloy foams. The intermetallic compounds were formed by solid-state diffusion between the metal powder elements. Mg17Al12 intermetallics was the most stable compound formed in the cell walls of porous Mg alloy foams. The addition of Zn influences the solubility and stability of the intermetallic compound. Thermodynamic calculations show that Mg17Al12 was preferentially formed in the cell walls owing to its high negative enthalpy energy. Moreover, various metastable transition phases may exist in the microstructures, especially in the porous Mg-9Al-5Zn alloy foam. The intermetallic phases act as reinforcing phases, combined with grain refinement, significantly increasing the strength of the foam. At the given relative density of 0.42, the porous Mg-9Al-5Zn alloy foam exhibits the highest yield strength of 9.0 MPa, which is 23% higher than the strength of the porous Mg-9Al-1Zn alloy foam.

Coupling High Rate Capability and High Capacity in an Intercalation-Type Sodium-Ion Hybrid Capacitor Anode Material of Hydrated Vanadate via Interlayer-Cation Engineering.

Layered metal vanadates with intercalation pseudocapacitive behaviors show great promise for applications in sodium-ion hybrid capacitor anode materials due to their large interlayer distances, which benefit the fast Na+ solid-state diffusion. However, their charge storage capacity is significantly constrained by the limited available sites that allow the intercalation of Na+ ions. In this work, by engineering the interlayer cations, Ni0.12Zn0.2V2O5·1.07H2O is designed as a high-performance anode material in sodium-ion hybrid capacitors. The Ni/Zn codoping in the layered vanadate leads to the integration of high rate capability and high specific capacity. Specifically, the spacious interlayer spacing and the pillaring effects of Zn ions together lead to the high rate performance and decent cycling stability, while the redox reactions of the interlayer Ni ions efficiently upgrade the charge storage capacity of this layered material. Accordingly, this work offers a promising avenue to further optimizing the Na+ storage performance of layered vanadates via interlayer-cation engineering.

Abnormal interfacial bonding mechanisms of multi-material additive-manufactured tungsten–stainless steel sandwich structure

Tungsten (W) and stainless steel (SS) are well known for the high melting point and good corrosion resistance respectively. Bimetallic W–SS structures would offer potential applications in extreme environments. In this study, a SS→W→SS sandwich structure is fabricated via a special laser powder bed fusion (LPBF) method based on an ultrasonic-assisted powder deposition mechanism. Material characterization of the SS→W interface and W→SS interface was conducted, including microstructure, element distribution, phase distribution, and nano-hardness. A coupled modelling method, combining computational fluid dynamics modelling with discrete element method, simulated the melt pool dynamics and solidification at the material interfaces. The study shows that the interface bonding of SS→W (SS printed on W) is the combined effect of solid-state diffusion with different elemental diffusion rates and grain boundary diffusion. The keyhole mode of the melt pool at the W→SS (W printed on SS) interface makes the pre-printed SS layers repeatedly remelted, causing the liquid W to flow into the sub-surface of the pre-printed SS through the keyhole cavities realizing the bonding of the W→SS interface. The above interfacial bonding behaviours are significantly different from the previously reported bonding mechanism based on the melt pool convection during multiple material LPBF. The abnormal material interfacial bonding behaviours are reported for the first time.

Bottom-up fabrication of three-dimensional nanoporous gold from Au nanoparticles using nanowelding

Three-dimensional (3D) nanoporous gold (NPG) shows promising applications in various fields. However, its most common fabrication strategy (i.e., dealloying) faces the problems of high energy consumption, resource waste, the use of corrosive solvent, and residue of the sacrificial component. Here, we report a general bottom-up nanowelding strategy to fabricate high-purity NPG from Au nanoparticles (NPs), accomplished via interfacial self-assembly of the Au NPs into monolayer Au NP film, its subsequent layer-by-layer transfer onto a solid substrate, and direct current (DC) nanowelding. We show that the DC nanowelding process can gradually evolve the layered Au NP film into NPG at low temperatures within 10 s, while not damaging their spherical structure. This is because during the nanowelding, electrons are preferred to be localized at the high-resistance NP/NP junctions, whose electrostatic repulsion in turn strengthens their surface atom diffusion to initiate a mild solid-state diffusion nanowelding. Furthermore, when using differently sized Au NPs as the starting building blocks, this strategy allows readily tuning the thickness, ligament size, and pore size, thereby offering great flexibility to create functional porous nanomaterials, e.g., electrocatalyst for methanol electrooxidation. Surely, low-temperature nanowelding can play a role for the production of diverse nanoporous materials from other NPs beyond Au NPs.

Resolving the Seeming Contradiction between the Superior Rate Capability of Prussian Blue Analogues and the Extremely Slow Ionic Diffusion.

The superior rate capabilities of metal ion battery materials based on Prussian blue analogues (PBAs) are almost exclusively ascribed to the extremely fast solid-state ionic diffusion, which is possible due to structural voids and spacious three-dimensional channels in PBA structures. We performed a detailed electroanalytical study of alkali ion diffusivities in nanosized cation-rich and cation-poor PBAs obtained as particles or electrodeposited films in both aqueous and non-aqueous media, which resulted in a solid conclusion about the exceptionally slow ionic transport. We show that the impressive rate capability of PBA materials is determined solely by the small size of the primary particles of PBAs, while the apparent diffusion coefficients are 3-5 orders of magnitude lower than those reported in earlier studies. Our finding calls for a reconsideration of the apparent facility of ionic transport in PBA materials and deeper analysis of the charge carrier-host interactions in PBAs.

Lithiation and Magnesiation Mechanism of VOCl: First-Principles Moleculardynamics Simulation

The layered metal oxide VOCl is a kind of promising electrode material for rechargeable batteries. It is the first time that the thermodynamic, electronic, and kinetic properties of lithiated and magnesiated VOCl were systematically investigated. The upper limit of Li and Mg topological intercalation into VOCl is xLi = 1 and xMg = 0.5, respectively. Beyond the critical value, further lithiation and magnesiation will cause the phase evolution of layered VOCl. Upon lithiation, four discharge plateaus are observed at 2.10, 2.23, 1.62 and 1.23 V vs Li+/Li in the concentration range of 0 ≤ xLi ≤ 1. Upon magnesiation, the average voltage reaches 1.10 V vs Mg2+/Mg in the concentration range of 0 ≤ xMg ≤ 0.25, which are consistent with the experimental values. The pair correlation function (PCF) diagrams display the formation of V metal at high concentration of xLi and xMg, proving the occurrence of conversion reaction. The diffusion energy barriers of Li ions and Mg ions in VOCl are 0.22 and 0.72 eV, respectively, which are much lower than those of other intercalation materials. The layered VOCl bulk is a high-rate capability cathode material for lithium-ion battery. Based on the thermodynamic/kinetic properties and the AIMD simulation results, the electrochemical mechanism of layered VOCl is an intercalation-conversion reaction during the lithiated and magnesiated processes. The conversion-type cathodes have the potential to circumvent the sluggish solid-state Mg diffusion and improves the performance of Mg rechargeable batteries with high-energy density and high-rate capability.

Chemo-mechanical phase-field modeling of iron oxide reduction with hydrogen

The reduction of iron ore with carbon-carriers is one of the largest sources of greenhouse gas emissions in the industry, motivating global activities to replace the coke-based blast furnace reduction by hydrogen-based direct reduction (HyDR). Iron oxide reduction with hydrogen has been widely investigated both experimentally and theoretically. The HyDR process includes multiple types of chemical reactions, solid state and defect-mediated diffusion (of oxygen and hydrogen species), several phase transformations, as well as massive volume shrinkage and mechanical stress buildup. However, studies focusing on the chemo-mechanical interplay during the reduction reaction influenced by microstructure are sparse. In this work, a chemo-mechanically coupled phase-field (PF) model has been developed to explore the interplay between phase transformation, chemical reaction, species diffusion, large elasto-plastic deformation and microstructure evolution. Energetic constitutive relations of the model are based on the system free energy which is calibrated with the help of a thermodynamic database. The model has been first applied to the classical core-shell (wüstite-iron) structure. Simulations show that the phase transformation from wüstite to α-iron can result in high stresses and rapidly decelerating reaction kinetics. Mechanical stresses create elastic energy in the system, an effect which can negatively influence the phase transformations, thus causing slow reaction kinetics and low metallization. However, if the elastic stress becomes comparatively high, it can shift the shape of the free energy from a double-well to a single-well case, speed up the transformation and result in a higher reduction degree compared to the low-stress double-well case. The model has been applied to simulate an experimentally characterized iron oxide specimen with its complex microstructure. The observed microstructure evolution during reduction is well predicted by the model. The simulation results also show that isolated pores in the microstructure are filled with water vapor during reduction, which can influence the local reaction atmosphere and dynamics.

Partial transient liquid phase diffusion bonding of ZrC-SiC and 304 stainless steel by Ti/Ni interlayer: Microstructure and properties

The ZrC-SiC ceramic (ZS) was joined to 304 stainless steel (304SS) by using Ti/Ni interlayer. The joining process involves a transient liquid phase bonding at the ZS interface and a diffusion bonding at the 304SS interface. It is found TiCx grew fast on ZS interface or precipitated as particles in certain region of transient liquid, and its distribution and morphology were controlled by Ti gradient. Small amount of Si dissolved into liquid and then precipitated as Ti3Ni2Si with similar lattice structure to Ti2Ni. During solid-state diffusion, the TiNi reaction layer quickly transformed to refractory TiNi3 layer with a small number of Kirkendall pores and Ni5Zr phase at the TiNi3/Ni boundary. The underlying mechanism of interfacial reactions and microstructure evolution were proposed. The maximum shear strength of 97 ± 10 MPa was achieved when joining at 960 °C for 3 h. The failure mainly occurred along TiNi3/Ni boundary due to the presence of Kirkendall pores.

Solid-State Diffusion Bonding of Pseudo-α-Ti Alloy to Ti-Stabilized Stainless Steel: With and Without Interlayer

Solid-State Diffusion Bonding of Pseudo-α-Ti Alloy to Ti-Stabilized Stainless Steel: With and Without Interlayer