Post-deposition Heat Research Articles

Effect of post-deposition heat treatments on high-temperature wear and corrosion behavior of Inconel 625

This study uses the arc-directed energy deposition method to fabricate and heat treatment of a Ni-based Inconel 625 wall structure. Heat treatment involved solution treatment at 980°C with and without aging at 720°C, comparing results to the as-built condition. The effects of these heat treatments were analyzed through microstructural investigations, nanoindentation tests, and high-temperature wear and corrosion tests in 0.5 M NaCl and 0.5 M HCl solutions. In the as-built state, the Inconel 625 alloy exhibited a columnar dendritic structure predominantly composed of a gamma matrix along with Laves phase and MC carbides. Solution treatment dissolved the Nb-rich Laves phases and encouraged the formation of needle-like particles in regions with high Nb segregation, while also reducing voids and minimizing corrosion susceptibility along grain boundaries. This resulted in the formation of a uniform oxide layer on the surface, significantly enhancing wear and corrosion resistance. Both heat-treated samples showed improvements in mechanical ratios such as H/E, H³/E², and H²/2E in the WAAM-produced Inconel 625 alloy, resulting in a 67 % enhancement in wear resistance compared to the as-built sample. Corrosion tests also revealed that solution treated samples showed the highest corrosion resistance, followed by aged treatment and as-built samples, respectively. In conclusion, this study provides a thorough understanding of the substantial impact of heat treatments on the microstructure, mechanical properties, and corrosion resistance of Inconel 625, offering valuable insights for advancements in the field.

Improved material properties of wire arc additively manufactured Al-Zn-mg-cu alloy through severe deformation interlayer friction stir processing and post-deposition heat treatment

In this study, Al-Zn-Mg-Cu alloys were prepared by wire arc additive manufacturing (WAAM) combined with interlayer friction stir processing (IFSP). To enhance the FSP region, an improved stirring pin was designed to broaden the stir zone effectively. Moreover, the effects of typical T6 and T73 heat treatments on the microstructure and mechanical properties of as-deposited (AS) specimen were meticulously investigated. The results indicated that heat treatments had minimal impact on grain size, dislocation density, and texture strength, but significantly altered the type, size, and distribution of precipitates. The differences in strength were primarily attributed to precipitation strengthening rather than grain boundary or dislocation strengthening. Following T6 heat treatment, the precipitates were predominantly η’, which were smaller in size and exhibited a significantly increased number density compared to AS specimen. Therefore, the average yield strength (YS) and ultimate tensile strength (UTS) increased by 39.51 % (500.21 MPa) and 15.84 % (584.26 MPa), respectively. In contrast, T73 treatment caused a substantial number of fine η’ to transform into coarser η, leading to a significant decrease in precipitate number density. Consequently, compared to T6 specimen, the average YS and UTS decreased by 47.19 % and 13.13 %, respectively.

Impact of annealing on the characteristics of 3D-printed graphene-reinforced PLA composite

Manufacturing through additive techniques, especially utilizing the fused filament fabrication (FFF) method, is a transformative technology revolutionizing design and manufacturing. FFF builds parts layer by layer using thermoplastic polymer and polymer composite filaments. However, weak interlayer connections often lead to low interlaminar resistance in printed structures. Recent studies suggest that post-deposition heat treatments can mitigate this issue by reducing internal thermal stresses and enhancing layer adhesion, thereby improving part properties. This research delves into the impact of annealing heat treatment on a composite of Polylactic Acid (PLA) reinforced with graphene. The annealing process was conducted at temperatures of 90, 100, and 120 °C for durations of 60, 120, and 240 min. The annealing response of the graphene-reinforced PLA composite is compared to that of natural PLA for reference, analyzing its effects on electrical, thermal, chemical, and mechanical properties. Chemical characterization was performed using X-ray diffraction (XRD), Raman spectroscopy, and Fourier-transform infrared spectroscopy (FTIR). Thermal properties were analyzed via thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Electrical properties were assessed by measuring resistance, resistivity, and conductivity. Mechanical properties were evaluated through tensile, flexural, notch sensitivity, impact tests, and hardness measurements. The results demonstrated that annealing of graphene-reinforced PLA and natural PLA did not alter their functional groups but increased their crystallinity. This treatment improved thermal stability, electrical conductivity, and mechanical properties, including tensile strength, flexural strength, and Shore D hardness. However, it reduced impact and notch sensitivity resistances. The increased crystallinity had a greater beneficial impact on some properties than the graphene reinforcement. These findings have potential applications in the automotive, aerospace, electronics, and medical sectors, given the increasing use of PLA in these industries.

Mechanism of Ag-SiO2-TiO2 Nanocomposite Coating Formation on NiTi Substrate for Enhanced Functionalization

The functionality of the NiTi shape memory alloy was improved through engineering Ag-SiO2-TiO2 nanocomposite coatings. For this purpose, an anaphoretic deposition process, conducted at a constant voltage of 40 V and deposition times ranging from 1 to 10 min, was used. Scanning electron microscopy (SEM) analysis demonstrated that the deposition parameters significantly impacted the morphology of the coatings. Complementary Raman Spectroscopy and X-ray diffraction (XRD) analyses confirmed the successful formation of distinct nanocomposite layers, and revealed the details of their crystalline structure and chemical composition. After that, the adhesion between the NiTi substrate and the electrophoretically deposited ceramic coatings was improved through a post-deposition heat treatment. To prevent excessive shrinkage and cracking of the coating, tests were carried out to characterize the behavior of the coating material at elevated temperatures. The nanocomposite coatings were exposed to a temperature of 800 °C for 2 h. The annealing induced significant structural and morphological transformations, resulting in layers that were distinctly different from both the original materials and those produced solely through electrophoretic deposition. The thermal treatment resulted in the formation of a new kind of nanocomposite structure with enhanced reactivity.

Microstructure and fatigue crack growth behavior of heat-treated electron beam melted Ti-6Al-4V alloy

The effect of post-deposition heat treatment on microstructure and fatigue crack growth has been analyzed for electron beam melted Ti-6Al-4V plates. Samples have been heat-treated at temperatures of 950 °C and 1050 °C, and subsequently cooled at different cooling rates in the furnace and the water. The as-built sample possesses columnar prior β grains filled with exceptionally fine α+β Widmanstätten patterns and epitaxially grows in the vertical direction. Heat treatment with a slow cooling rate increases the α lath thickness, whereas fast cooling results in multiple needle-shaped α/α′ phases inside the prior β grains. The yield strength and ultimate tensile strength in as-built conditions are greater than the extruded mill annealed sample. The as-built samples show better crack growth resistance during the fatigue crack growth rate test than the heat-treated and mill-annealed samples. The lower plastic deformation of the as-built sample than the mill-annealed sample is attributed to the existence of fine α laths that restrict the motion of dislocation.

Microstructural stability and precipitate evolution of thermally treated 7075 aluminum alloy fabricated by cold spray

In this work, the effects of post-deposition heat treatment on microstructural stability of cold sprayed AA7075 aluminum coatings were thoroughly characterized. The as-atomized powder and annealed coatings were investigated using scanning electron microscopy, electron back-scattered diffraction, and microhardness measurements. Scanning transmission electron microscopy was further employed to evaluate grain/subgrain structure near the particle interface region. Precipitation in the coating was studied through differential scanning calorimetry and X-ray diffraction. The feedstock powder revealed dendritic/cellular-like structure accompanied by microsegregations of the main alloying elements at dendrite boundaries. The high-pressure Cold Spray process led to formation of lamellar subgrains and UFG grains via dynamic recovery/recrystallization mechanisms. GP zones present in the AA7075 powder continuously reprecipitated into more stable η´/η phases owing to propellant gas heating and extensive plastic strains induced during cold spraying. The applied annealing resulted in progressive softening of the AA7075 coatings and gradual transformation of LAGBs into HAGBs. The solute-rich grain boundary network observed in powder microstructure was fully retained after CS deposition but decomposed into coarse η and S precipitates upon high-temperature annealing. The CS AA7075 coating showed decent thermal stability up to 300 °C and rapid grain growth at 400 °C. The relationship between precipitate size and thermal stability was further discussed in terms of the Zener pinning theory.

Investigating the influence of post-deposition heat treatment (PDHT) on the characteristic changes in wire arc additively manufactured 410 martensitic stainless steel thin-wall structure

Obtaining the desired material characteristics of an as-deposited martensitic stainless steel (MSS) structure fabricated by wire arc additive manufacturing (WAAM) is challenging due to several factors like inhomogeneity, precipitation, phase transition, etc. This investigation elucidates the impact of post-deposition heat treatment (PDHT) on the microstructural and mechanical properties of the WAAM-processed 410 MSS thin-wall structure and compares it with the as-deposited 410 thin-wall structure. The MSS thin-wall structure consists of retained austenite (γ), delta (δ) ferrite, martensite laths and Cr-rich M23C6 type carbide. The M23C6 volume fraction increases by up to 18 %, and the γ-phase fraction reduces by up to 40 % by applying PDHT. The PDHT process significantly changed the texture from {110}<011> to {001}<110>. The PDHT process increases the dislocation density (1.974 × 10−15 m−2) than the as-deposited condition (0.924 × 10−15 m−2). The total low energy boundary (LAGB+CSL) contribution of the as-deposited sample is 19.5 %, whereas the PDHT sample demonstrated a higher fraction of low energy boundaries of 32.4 %. The PDHT sample showed a much smaller distribution of grains with an average grain size of 11 μm compared to the as-deposited condition. The overall hardness increases from 468 HV to 487 HV after PDHT compared to the as-deposited condition with lower inhomogeneity across the build direction. The mean 0.2 % proof stress, ultimate tensile stress, and elongation of the PDHT sample increased by 17 %, 5 %, and 60 %, respectively, compared to the as-deposited sample.

Effect of post-deposition heat treatments on the microstructure and tensile properties of wire-fed electron beam directed energy deposition GH4169 Ni-based alloy

The microstructure and tensile properties of GH4169 alloy fabricated by wire-fed electron beam directed energy deposition (EB-DED) were investigated in both as-deposited (As-Dep) and homogenization plus double aging heat treatment (HA) condition. The results show that thermal cycling caused an aging effect in the As-Dep samples, resulting in the precipitation of the γ’/γ” phases in close proximity to the Laves phase. The dissolution behavior of Laves phase in GH4169 alloy at various homogenization heat treatment temperatures and holding times was studied. Based on experimental results and Johnson-Mehl-Avramie-Kolmogorov (JMAK) analysis, the dissolution activation energy of Laves phase was calculated as 218.2 kJ/mol. The heat treatment regime utilized in HA treatment consisted of 1150 °C × 60 min/WC + 720 °C × 8 h/FC to 620 °C × 8 h/WC. After HA treatment, most of the Laves phases were dissolved and the γ’/γ” phases were precipitated. The mechanical properties of HA samples are superior to those of As-Dep samples. The morphology, distribution and evolutionary mechanism of the Laves phase, γ’/γ” phases are discussed and analyzed.

Impact of post deposition treatment on optoelectrical and microstructural properties of tin sulfide thin film for photovoltaic applications

Tin sulfide (SnS) has attracted significant interest due to its advantageous optoelectrical characteristics and abundant presence in nature. Post-deposition treatments (PDTs) are frequently employed to enhance the crystallinity of chalcogenide-based solar cells. This study examined the influence of the post-deposition heat treatment procedure on thermally evaporated SnS thin film. The post-deposition annealing process, as determined by XRD and AFM studies, supplies the necessary thermal energy for re-crystallization, potentially resulting in a modification of crystallite dimensions. The occurrence of Sn-S polytypes was examined using Raman and XPS studies. Annealing causes changes in the optical properties, as observed through optical analysis, which can be attributed to the improvement in crystallinity. Subjecting the material to annealing at temperature of 300 °C greatly improves both mobility and conductivity, while also causing a change in conduction type. The observed variations in conduction type are attributed to the differing ratios between the amounts of Sn2+ and Sn4+. This strategy offers a novel route for the fabrication of thin-film photovoltaic cells by using a p-type buffer layer.

Study of surface structure and interfacial effects on optical and magnetic properties of un-doped and Si-doped hematite films

Thermal evaporation technique has been used to synthesize the α-Fe2O3 (hematite) and Si-doped hematite films on three different substrates (SiO2/Si, Al2O3 and quartz). The post-deposition heat treatment at 800 °C has further improved the crystalline nature of the films. Rutherford backscattering spectroscopy has provided information for surface elemental composition and depth profile. Raman spectra have supported the formation of rhombohedral phase and inter-layer diffusion between substrate and films. The x-ray photoelectron spectroscopy has confirmed the mixed-valence oxidation states for Fe ions and +4 state for the Si ions in Si-doped hematite films. The optical reflectance spectra in the UV–Visible region indicated contributions from the films and film-substrate interface. The Si-doping has enhanced soft ferromagnetic properties in the hematite film with noticeable decrease of the magnetic coercivity and increase of the magnetic moment. The films showed blocking of magnetization at lower temperatures, typically below 125 K, and a wide thermomagnetic irreversibility between zero-field cooled and field cooled magnetization curves. The modified surface chemical structure, ferromagnetism and optical properties in the Si doped hematite films promise their potential applications in spintronics.

High-performance Ni-based superalloy 718 fabricated via arc plasma directed energy deposition: effect of post-deposition heat treatments on microstructure and mechanical properties

Ni-based superalloy 718 fabricated via arc plasma direct energy deposition (IN718 AP-DED) exhibit a limited response to heat treatment due to its coarse primary microstructure and interdendritic segregation, which may prevent its use in high-integrity applications. Thus, dedicated heat treatments for IN718 AP-DED must possess a homogenization temperature as high as possible to significantly dissolve the eutectics and increase the γ′′-former elements in solid-solution. The present work proposed heat treatments for IN718 AP-DED (homogenization – 1050, 1100, 1142, and 1185 °C / 2 h – followed by aging – 718 °C / 8 h, cooling at 56 °C / h, and 621 °C / 8 h). The as-built IN718 AP-DED showed the typical coarse and oriented (cube texture) microstructure with eutectics (Laves and MC-typical carbides) in the interdendritic region, which were significantly dissolved during the homogenization, promoting a high-volume fraction of hardening phase (γ′′ and γ′) and outstanding quasi-static mechanical properties after the aging step. The present work showed that IN718 AP-DED mechanical properties can be optimized through dedicated heat treatments, meeting the ductility and yield strength requirements (room temperature) of AMS 5662. Furthermore, the heat treatments did not alter the grain morphology and texture aspect, inducing a lower Young’s modulus compared to the non-oriented material.

Micromechanical Analysis of Metal-Ceramic Thin-Films on Steel Substrates

Thin-layered coatings on material surfaces can resist contact forces and provide protection against material wear. In this study, FeCrNi-Al2O3 composite coatings were prepared by electrodeposition onto a 316L steel substrate. The effects of electrodeposition cathode current density (3 A·dm−2, 5 A·dm−2, 7 A·dm−2 and 9 A·dm−2) and post annealing at 500°C in Ar atmosphere were investigated. An increase in deposition rate resulted in a rougher coating surface and a thicker coating at a constant deposition duration. Post-deposition heat treatment caused the surface roughness to increase because of the introduction of denser micro-cracks. Higher current densities improved adhesion and prevented angled cracks during scratching, while annealing led to scratching-induced failures at lower applied loads. FeCrNi-Al2O3 composite coatings showed higher hardness but lower Young's modulus compared to the steel substrate. The coating hardness is slightly enhanced by increasing the electrodeposition current density from 5 A·dm−2 to 9 A·dm−2, and a more significant increase is observed after annealing. However, the hardness is negatively impacted by the combined effect of annealing and higher current density. These findings demonstrate the importance of carefully balancing the electrodeposition current density and annealing conditions to achieve optimal coating properties. To optimize metal-ceramic composite coatings, it is crucial to investigate multiple process parameters that may interact with each other.

Non-stoichiometric silicon nitride for future gravitational wave detectors

Silicon nitride thin films were deposited at room temperature employing a custom ion beam deposition (IBD) system. The stoichiometry of these films was tuned by controlling the nitrogen gas flow through the ion source and a process gas ring. A correlation is established between the process parameters, such as ion beam voltage and ion current, and the optical and mechanical properties of the films based on post-deposition heat treatment. The results show that with increasing heat treatment temperature, the mechanical loss of these materials as well as their optical absorption decreases producing films with an extinction coefficient as low as k=6.2(±0.5)×10−7 at 1064 nm for samples annealed at 900 ∘C. This presents the lowest value for IBD SiN x within the context of gravitational wave detector applications. The mechanical loss of the films was measured to be ϕ=2.1(±0.6)×10−4 once annealed post deposition to 900 ∘C.

Effect of Heat Treatment on the Electrochemical and Tribological Properties of Aluminum-Bronze Coatings Deposited Used the Thermal Spraying Process

The corrosion and wear resistance of aluminum-bronze coatings deposited by thermal flame spraying were investigated after a 10 h heat treatment at 500 °C in a nitrogen atmosphere. The coatings were characterized by SEM, EDS, XRD, and XRF. Corrosion resistance was evaluated by Tafel and EIS tests, while wear resistance was assessed using a ball-on-disc test. Results showed the heat treatment compacted the coating microstructure, increased oxide content, and improved splat bonding through diffusion mechanisms. This led to enhanced corrosion resistance, evidenced by reduced corrosion current density in electrochemical tests, resulting from densification impeding electrolyte penetration. Heat treatment also increased wear resistance, as indicated by lower wear rates in ball-on-disc tests, attributable to increased hardness, reduced friction coefficients, and annealing-induced microstructural changes. Overall, the heat treatment optimizes the anticorrosive and tribological properties of thermally sprayed aluminum-bronze coatings via favorable alterations in composition, morphology, and physical characteristics. The research provides a new understanding of how thermal spray parameters and post-deposition heat treatment can be utilized to enhance the corrosion and wear resistance of aluminum-bronze coatings for marine applications.

Effect of post-deposition heat treatment on microstructure and mechanical properties of NASA HR-1 cold spray coatings

The primary goal of this work was to examine the impact of heat treatment on the evolution of microstructure and mechanical properties of NASA HR-1 cold spray coatings. Coatings were produced employing a high-pressure cold spray system using N2 and He process gases and the effect of process gas and deposition temperature on the microstructure and mechanical properties of the coatings was examined. Microstructural characterization was performed using optical microscopy, scanning electron microscopy, micro X-ray computed tomography, and electron backscatter diffraction. NASA HR-1 coatings produced with He process gas exhibited improved plastic deformation and resulted in the lowest porosity compared to those deposited with N2 process gas. All coatings showed brittle failure with limited ductility in the as-deposited condition. Heat treatment of the NASA HR-1 cold spray coatings was performed at 550 °C and 950 °C for 1 h to improve the mechanical strength of the coatings. Heat treatment improved the particle bonding and enhanced the mechanical properties of the cold spray coatings. Heat treatment performed at 550 °C resulted in higher mechanical strength of coatings, whereas the heat treatment performed at 950 °C resulted in recrystallized microstructure and improved ductility of the coatings. However, heat treatment at 950 °C resulted in forming the Eta (η) phase and Ni-Ti intermetallics in all the NASA HR-1 cold spray coatings. The overall results suggest that using He as process gas contributed to reduced porosity and enhanced mechanical properties of the cold spray coatings.

Effect of Post-Deposition Heat Treatment on the Mechanical Behavior and Deformation Mechanisms of a Solid-State Additively Manufactured Al–Mg–Si Alloy

Abstract The effects of post-deposition heat treatment on the fatigue behavior of AA6061 processed by additive friction stir deposition (AFSD) were investigated for the first time in this work. A heat treatment to recover the T6 temper was performed on AFSD AA6061 is then subjected to strain-controlled fatigue and monotonic tension testing. Microstructural analysis revealed abnormal grain growth resulting in bimodal grain size distribution. Mechanical testing indicated a full recovery of the strength of the AA6061-T6 temper with comparable fatigue performance to the as-deposited AFSD AA6061. Fractography revealed deformation mechanisms in the post-deposition heat treatment not observed in the as-deposited samples, however, the fatigue resistance remained unchanged. A microstructure-sensitive fatigue model was implemented to capture the effects of the heat treatment process on the fatigue performance of the post-deposition heat-treated AFSD AA6061.

Feasibility study of wire arc additive manufactured P91 steel by cold metal transfer deposition

The objective of this study was to analyze and evaluate the feasibility of utilizing Wire Arc Additive Manufacturing (WAAM) technology for the constructing components made from P91 steel, which is widely used material for high-temperature applications. The utilization of the Cold Metal Transfer (CMT) method enables the deposition of thin steel walls by virtue of its low heat input. Samples collected from the deposited wall have been tested in two different microstructural conditions, in the as-built (AB) condition and in a normalized and tempered (NT) condition. The latter condition is the microstructural state commonly employed for producing components used in power plants. This post-deposition heat treatments (PDHT) comprise a normalization process conducted at 1050 °C for 40 min, followed by a tempering step at 760 °C for 2 h. The results of mechanical testing and microstructural characterization were then compared against the established standards for commercial P91 steel. SEM-EDAX, XRD, and EBSD analyses were employed to conduct a comprehensive microstructural examination of the samples. The hardness of the AB samples ranged from 384 to 439 HV, while the NT samples had a hardness range of 205 to 223 HV. In terms of tensile strength, the AB samples demonstrated a range of 1064 to 1266 MPa, whereas the NT samples exhibited a range of 635 to 626 MPa. These results were found to be consistent with the observed strong texture and grain orientations in the {001} and {111} planes, as revealed by the EBSD analysis. The NT components demonstrated significant strength, ductility, hardness, and toughness compared to the specified ASTM standards. Based on the test performance and feasibility criteria, this process has significant potential as an additive manufacturing method suitable for complex boiler components.

Study on residual OH content in low-temperature Si oxide films after in situ post-deposition heating (PDH)

We investigated the post-deposition heating (PDH) effect on OH content in SiOx films deposited by atmospheric-pressure CVD using a deposition source of silicone oil (SO) with O3 and TCE vapor at a temperature T d of 180 °C–250 °C. The PDH is performed in situ for 5 min in the deposition chamber just after film deposition without any supply of SO, where the heating temperature is the same as T d. The OH content in the films deposited normally decreases with increasing T d. In contrast, those with PDH decrease with deceasing T d from 220 °C, and, at T d = 190 °C, a minimum OH content can be obtained. This means that lower OH content remains at a lower deposition temperature. The PDH effect on OH reduction can be explained by easily reconstructible structure of SiOx films deposited at low temperature. Furthermore, we discuss the mechanism of the PDH effect from other points of view.

Understanding the Effects of Post-Deposition Sequential Annealing on the Physical and Chemical Properties of Cu2ZnSnSe4 Thin Films

Cu2ZnSnSe4 thin films have been synthesized by employing two magnetron-sputtering depositions, interlaced with two sequential post-deposition heat treatments in low vacuum, Sn+Se and Se–rich atmospheres at 550 °C. By employing successive structural analysis methods, namely Grazing Incidence X–Ray Diffraction (GIXRD) and Raman Spectroscopy, secondary phases such as ZnSe coexisting with the main kesterite phase have been identified. SEM peered into the surface morphology of the samples, detecting structural defects and grain profiles, while EDS experiments showed off–stoichiometric elemental composition. The optical bandgaps in our samples were calculated by a widely used extrapolation method from recorded transmission spectra, holding values from 1.42 to 2.01 eV. Understanding the processes behind the appearance of secondary phases and occurring structural defects accompanied by finding ways to mitigate their impact on the solar cells’ properties is the prime goal of the research beforehand.

Enhanced Carrier Collection in Cd/In-Based Dual Buffers in Kesterite Thin-Film Solar Cells from Nanoparticle Inks.

Increasing the power conversion efficiency (PCE) of kesterite Cu2ZnSn(S,Se)4 (CZTSSe) solar cells has remained challenging over the past decade, in part due to open-circuit voltage (VOC)-limiting defect states at the absorber/buffer interface. Previously, we found that substituting the conventional CdS buffer layer with In2S3 in CZTSSe devices fabricated from nanoparticle inks produced an increase in the apparent doping density of the CZTSSe film and a higher built-in voltage arising from a more favorable energy-band alignment at the absorber/buffer interface. However, any associated gain in VOC was negated by the introduction of photoactive defects at the interface. This present study incorporates a hybrid Cd/In dual buffer in CZTSSe devices that demonstrate an average relative increase of 11.5% in PCE compared to CZTSSe devices with a standard CdS buffer. Current density-voltage analysis using a double-diode model revealed the presence of (i) a large recombination current in the quasi-neutral region (QNR) of the CZTSSe absorber in the standard CdS-based device, (ii) a large recombination current in the space-charge region (SCR) of the hybrid buffer CZTSSe-In2S3-CdS device, and (iii) reduced recombination currents in both the QNR and SCR of the CZTSSe-CdS-In2S3 device. This accounts for a notable 9.0% average increase in the short-circuit current density (JSC) observed in CZTSSe-CdS-In2S3 in comparison to the CdS-only CZTSSe solar cells. Energy-dispersive X-ray, secondary-ion mass spectroscopy, and grazing-incidence X-ray diffraction compositional analysis of the CZTSSe layer in the three types of kesterite solar cells suggest that there is diffusion of elemental In and Cd into the absorbers with a hybrid buffer. Enhanced Cd diffusion concomitant with a double postdeposition heat treatment of the hybrid buffer layers in the CZTSSe-CdS-In2S3 device increases carrier collection and extraction and boosts JSC. This is evidenced by electron-beam-induced current measurements, where higher current generation and collection near to the p-n junction is observed, accounting for the increase in JSC in this device. It is expected that optimization of the heat treatment of the hybrid buffer layers will lead to further improvements in the device performance.