Pub Date : 2025-02-13DOI: 10.1016/j.mtla.2025.102372
M. Odnobokova , P. Dolzhenko , N. Enikeev , R.Z. Valiev , R. Kaibyshev , A. Belyakov
The deformation behavior of a warm rolled 304L-type austenitic stainless steel was studied by means of tensile tests at temperatures of 213 – 293 K. The starting material was subjected to warm rolling to a strain of 0.5 at 573 K. This warm working promoted the α'-martensite formation upon subsequent tensile tests at lowered temperatures owing to shortening the transformation critical strain. The fraction of α'-martensite comprised more than 0.2 after tension to a strain of 0.3 at 293 K, whereas that was above 0.8 at 213 K. Moreover, the cold deformation was accompanied by twinning and the development of strain-induced grain boundaries leading to submicrocrystalline microstructure evolution. The deformation behavior during tensile tests was characterized by a rapid increase in the flow stress in the strain range of 0.1 – 0.25 that was more pronounced at a lower temperature. The tensile flow stress could be related to the dislocation density, which in turn can be expressed by a function of strain, taking into account the grain subdivision by strain-induced boundaries and martensitic transformation.
{"title":"On the low temperature deformation behavior of a warm rolled 304L-type stainless steel","authors":"M. Odnobokova , P. Dolzhenko , N. Enikeev , R.Z. Valiev , R. Kaibyshev , A. Belyakov","doi":"10.1016/j.mtla.2025.102372","DOIUrl":"10.1016/j.mtla.2025.102372","url":null,"abstract":"<div><div>The deformation behavior of a warm rolled 304L-type austenitic stainless steel was studied by means of tensile tests at temperatures of 213 – 293 K. The starting material was subjected to warm rolling to a strain of 0.5 at 573 K. This warm working promoted the α'-martensite formation upon subsequent tensile tests at lowered temperatures owing to shortening the transformation critical strain. The fraction of α'-martensite comprised more than 0.2 after tension to a strain of 0.3 at 293 K, whereas that was above 0.8 at 213 K. Moreover, the cold deformation was accompanied by twinning and the development of strain-induced grain boundaries leading to submicrocrystalline microstructure evolution. The deformation behavior during tensile tests was characterized by a rapid increase in the flow stress in the strain range of 0.1 – 0.25 that was more pronounced at a lower temperature. The tensile flow stress could be related to the dislocation density, which in turn can be expressed by a function of strain, taking into account the grain subdivision by strain-induced boundaries and martensitic transformation.</div></div>","PeriodicalId":47623,"journal":{"name":"Materialia","volume":"39 ","pages":"Article 102372"},"PeriodicalIF":3.0,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143419597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-13DOI: 10.1016/j.mtla.2025.102374
J. Bonnal , C. Petitjean , P.J. Panteix , L. Saint-Jean , D. Bonina , S. Arnal , M. Vilasi
The durability of the ceramic coatings used to protect the turbine blades in the field of aeronautical engines is strongly linked to their ability to withstand corrosion by calcium-magnesium-aluminosilicates (i.e. CMAS), which can infiltrate their microstructure when liquid at high temperature. Protection can be provided thanks to the high reactivity of the ceramic coatings with CMAS leading to the fast precipitation of protective phases. Most ceramic coatings contain rare-earth elements (e.g. rare-earth monosilicates RE2SiO5 or rare-earth disilicates RE2Si2O7), making them thus able to form oxyapatite after reaction with the silicate melts. The present works proposes to study the morphology of these precipitated phases depending on the nature of the rare-earth source. A model ternary melt CaO-Al2O3-SiO2 has thus been put in contact at 1300 °C with different sources of yttrium: oxide Y2O3, monosilicate Y2SiO5 and disilicate Y2Si2O7. The reactivity led to the precipitation of the two phases of interest (i.e. apatite Ca2Y8(SiO4)6O2 and cyclosilicate Ca3Y2(Si3O9)2). The use of these simplified systems allows to establish the precipitation mechanisms of the phases at equilibrium regarding previously established phase diagrams. Depending on the yttrium source, the chemical reactions involved local modifications of the melt composition, which strongly influenced the morphology of the precipitated phases at equilibrium. Specifically, it is demonstrated here that the release of SiO2 in the melt when starting from yttrium disilicate involves a specific microstructure of the acicular apatite, which exhibits a core containing precipitated SiO2.
{"title":"Influence of the source of yttrium on the morphology of precipitated phases after interaction with a CaO-Al2O3-SiO2 melt at 1300°C","authors":"J. Bonnal , C. Petitjean , P.J. Panteix , L. Saint-Jean , D. Bonina , S. Arnal , M. Vilasi","doi":"10.1016/j.mtla.2025.102374","DOIUrl":"10.1016/j.mtla.2025.102374","url":null,"abstract":"<div><div>The durability of the ceramic coatings used to protect the turbine blades in the field of aeronautical engines is strongly linked to their ability to withstand corrosion by calcium-magnesium-aluminosilicates (i.e. CMAS), which can infiltrate their microstructure when liquid at high temperature. Protection can be provided thanks to the high reactivity of the ceramic coatings with CMAS leading to the fast precipitation of protective phases. Most ceramic coatings contain rare-earth elements (e.g. rare-earth monosilicates RE<sub>2</sub>SiO<sub>5</sub> or rare-earth disilicates RE<sub>2</sub>Si<sub>2</sub>O<sub>7</sub>), making them thus able to form oxyapatite after reaction with the silicate melts. The present works proposes to study the morphology of these precipitated phases depending on the nature of the rare-earth source. A model ternary melt CaO-Al<sub>2</sub>O<sub>3</sub>-SiO<sub>2</sub> has thus been put in contact at 1300 °C with different sources of yttrium: oxide Y<sub>2</sub>O<sub>3</sub>, monosilicate Y<sub>2</sub>SiO<sub>5</sub> and disilicate Y<sub>2</sub>Si<sub>2</sub>O<sub>7</sub>. The reactivity led to the precipitation of the two phases of interest (i.e. apatite Ca<sub>2</sub>Y<sub>8</sub>(SiO<sub>4</sub>)<sub>6</sub>O<sub>2</sub> and cyclosilicate Ca<sub>3</sub>Y<sub>2</sub>(Si<sub>3</sub>O<sub>9</sub>)<sub>2</sub>). The use of these simplified systems allows to establish the precipitation mechanisms of the phases at equilibrium regarding previously established phase diagrams. Depending on the yttrium source, the chemical reactions involved local modifications of the melt composition, which strongly influenced the morphology of the precipitated phases at equilibrium. Specifically, it is demonstrated here that the release of SiO<sub>2</sub> in the melt when starting from yttrium disilicate involves a specific microstructure of the acicular apatite, which exhibits a core containing precipitated SiO<sub>2</sub>.</div></div>","PeriodicalId":47623,"journal":{"name":"Materialia","volume":"39 ","pages":"Article 102374"},"PeriodicalIF":3.0,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143419596","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-12DOI: 10.1016/j.mtla.2025.102373
J.J. Mao , L. Liu , Z.Y. Liang
Here, we explored the mechanical behavior and microstructural evolution of a ferrite-austenite duplex medium Mn steel under extremely high strain rate (103 s-1). It is found that the yield strength increases by 135 MPa with the increase of strain rate from 10–3 to 103 s-1. Yet, the strain hardening rate decreases significantly, resulting in a lower ultimate tensile strength and a reduced uniform elongation. Microstructural analysis and thermodynamic calculations reveal that dislocation multiplication is promoted by high-strain-rate deformation at the small strain of 4.0 %. At large strains, adiabatic heating causes a substantial temperature increase, reaching 367 K at the engineering strain of 25.9 %. This temperature rise leads to a significant increase in the stacking fault energy of austenite, suppressing transformation-induced plasticity effect. The elevated temperature also enhances dynamic recovery of dislocations, inhibiting dislocation multiplication during high-strain-rate deformation. As a result, the suppressions of both transform-induced plasticity effect and dislocation multiplication result in the decrease of strain hardening rate.
{"title":"Effect of strain rate on mechanical properties and microstructural evolution in a ferrite austenite duplex medium Mn steel","authors":"J.J. Mao , L. Liu , Z.Y. Liang","doi":"10.1016/j.mtla.2025.102373","DOIUrl":"10.1016/j.mtla.2025.102373","url":null,"abstract":"<div><div>Here, we explored the mechanical behavior and microstructural evolution of a ferrite-austenite duplex medium Mn steel under extremely high strain rate (10<sup>3</sup> s<sup>-1</sup>). It is found that the yield strength increases by 135 MPa with the increase of strain rate from 10<sup>–3</sup> to 10<sup>3</sup> s<sup>-1</sup>. Yet, the strain hardening rate decreases significantly, resulting in a lower ultimate tensile strength and a reduced uniform elongation. Microstructural analysis and thermodynamic calculations reveal that dislocation multiplication is promoted by high-strain-rate deformation at the small strain of 4.0 %. At large strains, adiabatic heating causes a substantial temperature increase, reaching 367 K at the engineering strain of 25.9 %. This temperature rise leads to a significant increase in the stacking fault energy of austenite, suppressing transformation-induced plasticity effect. The elevated temperature also enhances dynamic recovery of dislocations, inhibiting dislocation multiplication during high-strain-rate deformation. As a result, the suppressions of both transform-induced plasticity effect and dislocation multiplication result in the decrease of strain hardening rate.</div></div>","PeriodicalId":47623,"journal":{"name":"Materialia","volume":"39 ","pages":"Article 102373"},"PeriodicalIF":3.0,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143419599","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-11DOI: 10.1016/j.mtla.2025.102370
Debashish Sur , Samuel B. Inman , Kaitlyn L. Anderson , Nathan C. Smith , Matthew S. Barbieri , Jie Qi , Christopher M. Wolverton , John R. Scully
Passivation induced corrosion resistance of non-equiatomic BCC Fe-Cr-Al-Ti alloys, including critical passivator concentration, the roles of each alloying element, and possible synergies between the passivating components, i.e., Ti, Cr, and Al are presented. Two solid-solution BCC alloy series: Fe-8Cr-8Al-xTi and Fe-xCr-{16-x}Al-8Ti, where x was varied from 0 to 16 at.%, were investigated in acidified 0.1 M Na2SO4(aq) solutions. Short- and long-term passivation behaviors and oxide passive film chemistry were characterized. Alloys with at least 4 at.% Ti with 8 at.% both Cr and Al; or 8 at.% Ti with a Cr/Al ratio higher than 0.5 exhibited excellent corrosion resistance in pH 1 solution having a lower currrent density than 304L stainless steel. Ti additions to Fe-Cr-Al alloys were predicted to not only function as a passivating species but also to act as a species that alters the chemical short-range order by clustering of Cr-Cr pairs in their 1st nearest neighbors’ arrangement. This could be forecast using a “Coherent Ordering Descriptor” based on Monte Carlo simulations supported by first-principles Density Functional Theory calculations. The possibility of a new Ti containing highly corrosion-resistant low-cost stainless steel with only 4 at.% Ti and 8 at.% Cr while using 88 at.% inexpensive Fe and Al is suggested. Two underlying mechanisms describing the enhanced passivation behaviors are discussed based on the chemical short-range ordering of Cr atoms, and passive film stability provided by mixed oxide species, suggesting concepts useful for designing new lightweight corrosion-resistant alloys.
{"title":"Factors governing passivation behavior of Fe-Cr-Al-Ti alloys in sulfate containing acidified solutions: Uncovering the many roles of Ti","authors":"Debashish Sur , Samuel B. Inman , Kaitlyn L. Anderson , Nathan C. Smith , Matthew S. Barbieri , Jie Qi , Christopher M. Wolverton , John R. Scully","doi":"10.1016/j.mtla.2025.102370","DOIUrl":"10.1016/j.mtla.2025.102370","url":null,"abstract":"<div><div>Passivation induced corrosion resistance of non-equiatomic BCC Fe-Cr-Al-Ti alloys, including critical passivator concentration, the roles of each alloying element, and possible synergies between the passivating components, i.e., Ti, Cr, and Al are presented. Two solid-solution BCC alloy series: Fe-8Cr-8Al-<em>x</em>Ti and Fe-<em>x</em>Cr-{16-<em>x</em>}Al-8Ti, where <em>x</em> was varied from 0 to 16 at.%, were investigated in acidified 0.1 M Na<sub>2</sub>SO<sub>4(aq)</sub> solutions. Short- and long-term passivation behaviors and oxide passive film chemistry were characterized. Alloys with at least 4 at.% Ti with 8 at.% both Cr and Al; or 8 at.% Ti with a Cr/Al ratio higher than 0.5 exhibited excellent corrosion resistance in pH 1 solution having a lower currrent density than 304L stainless steel. Ti additions to Fe-Cr-Al alloys were predicted to not only function as a passivating species but also to act as a species that alters the chemical short-range order by clustering of Cr-Cr pairs in their 1<sup>st</sup> nearest neighbors’ arrangement. This could be forecast using a “Coherent Ordering Descriptor” based on Monte Carlo simulations supported by first-principles Density Functional Theory calculations. The possibility of a new Ti containing highly corrosion-resistant low-cost stainless steel with only 4 at.% Ti and 8 at.% Cr while using 88 at.% inexpensive Fe and Al is suggested. Two underlying mechanisms describing the enhanced passivation behaviors are discussed based on the chemical short-range ordering of Cr atoms, and passive film stability provided by mixed oxide species, suggesting concepts useful for designing new lightweight corrosion-resistant alloys.</div></div>","PeriodicalId":47623,"journal":{"name":"Materialia","volume":"39 ","pages":"Article 102370"},"PeriodicalIF":3.0,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143438234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-08DOI: 10.1016/j.mtla.2025.102366
Zihan Liu , Ning Li , Yingchun Jiang , Chenglin Yi , Cheol Park , Catharine C. Fay , Huck Beng Chew , Changhong Ke
We investigate the interfacial interaction in titanium metal matrix composites (MMCs) reinforced with boron nitride nanotubes (BNNTs) through in situ scanning electron microscopy nanomechanical pullout experiments. The measurements reveal a stronger interface formed by Ti with BNNTs than carbon nanotubes (CNTs). Density functional theory (DFT) calculations reveal that the observed interfacial strength is attributed to covalent bonding formed on the metal surface that is partially oxidized due to passivation. Moreover, the composite interface maintains its strength even after prolonged thermal annealing in air, which is in stark contrast to the substantial degradation that occurs on the composite interface with CNTs. The complex interplay of metal passivation on the interfacial interaction and reinforcement opens a new avenue of exploiting metal passivation as an innovative active self-strengthening mechanism for nanotube-reinforced MMCs.
{"title":"Metal passivation strengthens the interface in titanium composites reinforced with boron nitride nanotubes","authors":"Zihan Liu , Ning Li , Yingchun Jiang , Chenglin Yi , Cheol Park , Catharine C. Fay , Huck Beng Chew , Changhong Ke","doi":"10.1016/j.mtla.2025.102366","DOIUrl":"10.1016/j.mtla.2025.102366","url":null,"abstract":"<div><div>We investigate the interfacial interaction in titanium metal matrix composites (MMCs) reinforced with boron nitride nanotubes (BNNTs) through in situ scanning electron microscopy nanomechanical pullout experiments. The measurements reveal a stronger interface formed by Ti with BNNTs than carbon nanotubes (CNTs). Density functional theory (DFT) calculations reveal that the observed interfacial strength is attributed to covalent bonding formed on the metal surface that is partially oxidized due to passivation. Moreover, the composite interface maintains its strength even after prolonged thermal annealing in air, which is in stark contrast to the substantial degradation that occurs on the composite interface with CNTs. The complex interplay of metal passivation on the interfacial interaction and reinforcement opens a new avenue of exploiting metal passivation as an innovative active self-strengthening mechanism for nanotube-reinforced MMCs.</div></div>","PeriodicalId":47623,"journal":{"name":"Materialia","volume":"39 ","pages":"Article 102366"},"PeriodicalIF":3.0,"publicationDate":"2025-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143394495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-08DOI: 10.1016/j.mtla.2025.102363
João Victor de S. Araujo , Mariana X. Milagre , José Wilmar Calderón-Hernández , Nathanael W. Morais , Isolda Costa
The effects of friction stir welding (FSW) on the corrosion resistance of the AA2098-T351 aluminum alloy were investigated through immersion and electrochemical tests in a 0.005 mol L⁻¹ NaCl solution. The findings revealed that the welding joint (WJ), which includes the thermomechanically affected zone (TMAZ) and stir zone (SZ), demonstrated superior localized corrosion resistance compared to the HAZ and BM. The SZ and TMAZ demonstrated cathodic behavior relative to the HAZ and BM. Furthermore, the differences in corrosion resistance among the isolated welding zones and their behavior under galvanic coupling were analyzed and discussed, highlighting the complex electrochemical interactions within the welded structure.
{"title":"Friction Stir welding effects on the corrosion resistance of the 2098-T351 alloy","authors":"João Victor de S. Araujo , Mariana X. Milagre , José Wilmar Calderón-Hernández , Nathanael W. Morais , Isolda Costa","doi":"10.1016/j.mtla.2025.102363","DOIUrl":"10.1016/j.mtla.2025.102363","url":null,"abstract":"<div><div>The effects of friction stir welding (FSW) on the corrosion resistance of the AA2098-T351 aluminum alloy were investigated through immersion and electrochemical tests in a 0.005 mol L⁻¹ NaCl solution. The findings revealed that the welding joint (WJ), which includes the thermomechanically affected zone (TMAZ) and stir zone (SZ), demonstrated superior localized corrosion resistance compared to the HAZ and BM. The SZ and TMAZ demonstrated cathodic behavior relative to the HAZ and BM. Furthermore, the differences in corrosion resistance among the isolated welding zones and their behavior under galvanic coupling were analyzed and discussed, highlighting the complex electrochemical interactions within the welded structure.</div></div>","PeriodicalId":47623,"journal":{"name":"Materialia","volume":"39 ","pages":"Article 102363"},"PeriodicalIF":3.0,"publicationDate":"2025-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143350754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Polycrystalline SiC can serve as a receiver substrate for the fabrication of engineered SiC wafers for power-electronics devices. These substrates must be as flat as possible for further processing. They can be fabricated by chemical vapor deposition (CVD) on a sacrificial substrate, which is then removed leaving a thick free-standing SiC film. When deposited by CVD, a residual intrinsic stress gradient develops through thickness of the film and results in the curvature of the free-standing film. In this study, we show that two mechanisms are responsible for the occurrence of such an intrinsic stress gradient. The first is due to a change of grain size through the film's thickness that in turn leads to a change of intrinsic stress during growth. The second mechanism is attributed to the continuous relaxation of the film during growth. Although a constant grain size through thickness can be achieved with appropriate process conditions to minimize the intrinsic stress gradient, the second mechanism occurs for any microstructure. Therefore, the intrinsic stress gradient and the resulting curvature of the free-standing films is difficult to avoid though it can be minimized through pertinent choices of growth conditions.
{"title":"Curvature of free-standing polycrystalline SiC thick films grown by CVD: On the origin of the residual stress gradient","authors":"Yann Gallou , Alexandre Potier , Didier Chaussende","doi":"10.1016/j.mtla.2025.102350","DOIUrl":"10.1016/j.mtla.2025.102350","url":null,"abstract":"<div><div>Polycrystalline SiC can serve as a receiver substrate for the fabrication of engineered SiC wafers for power-electronics devices. These substrates must be as flat as possible for further processing. They can be fabricated by chemical vapor deposition (CVD) on a sacrificial substrate, which is then removed leaving a thick free-standing SiC film. When deposited by CVD, a residual intrinsic stress gradient develops through thickness of the film and results in the curvature of the free-standing film. In this study, we show that two mechanisms are responsible for the occurrence of such an intrinsic stress gradient. The first is due to a change of grain size through the film's thickness that in turn leads to a change of intrinsic stress during growth. The second mechanism is attributed to the continuous relaxation of the film during growth. Although a constant grain size through thickness can be achieved with appropriate process conditions to minimize the intrinsic stress gradient, the second mechanism occurs for any microstructure. Therefore, the intrinsic stress gradient and the resulting curvature of the free-standing films is difficult to avoid though it can be minimized through pertinent choices of growth conditions.</div></div>","PeriodicalId":47623,"journal":{"name":"Materialia","volume":"39 ","pages":"Article 102350"},"PeriodicalIF":3.0,"publicationDate":"2025-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143350761","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Although Germanium devices have attracted attention for post-silicon device applications, they suffer from heat dissipation problems that hinder miniaturization. This study demonstrates the low-temperature and vacuum-free bonding of a germanium substrate with a diamond heat spreader, which has the highest thermal conductivity among solid materials. For efficient heat dissipation, we designed a bonding process at 200 °C using a reduction pre-bonding treatment instead of conventional oxidation. The process suppresses the formation of a germanium oxide layer at the bonding interface. This study demonstrates that germanium and diamond substrates are bonded through a 1.6-nm-thick amorphous intermediate layer. The shear stress reached 9.43 MPa, satisfying the MIL-STD-883E standard for microelectronics. As the germanium substrate can form atomic bonds with thermally conductive materials through a thin interfacial layer, it is expected that the bonding process of the HCl-dipped Ge device can contribute to future high-frequency devices.
{"title":"Low-temperature bonding of HCl-dipped Ge substrate with diamond heat-spreader through atomically thin layer","authors":"Yuki Minowa , Takashi Matsumae , Yuichi Kurashima , Hideki Takagi , Masanori Hayase","doi":"10.1016/j.mtla.2025.102369","DOIUrl":"10.1016/j.mtla.2025.102369","url":null,"abstract":"<div><div>Although Germanium devices have attracted attention for post-silicon device applications, they suffer from heat dissipation problems that hinder miniaturization. This study demonstrates the low-temperature and vacuum-free bonding of a germanium substrate with a diamond heat spreader, which has the highest thermal conductivity among solid materials. For efficient heat dissipation, we designed a bonding process at 200 °C using a reduction pre-bonding treatment instead of conventional oxidation. The process suppresses the formation of a germanium oxide layer at the bonding interface. This study demonstrates that germanium and diamond substrates are bonded through a 1.6-nm-thick amorphous intermediate layer. The shear stress reached 9.43 MPa, satisfying the MIL-STD-883E standard for microelectronics. As the germanium substrate can form atomic bonds with thermally conductive materials through a thin interfacial layer, it is expected that the bonding process of the HCl-dipped Ge device can contribute to future high-frequency devices.</div></div>","PeriodicalId":47623,"journal":{"name":"Materialia","volume":"39 ","pages":"Article 102369"},"PeriodicalIF":3.0,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143419595","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-07DOI: 10.1016/j.mtla.2025.102367
R. Basumatary , P. Kalita , H. Bailung , R. Brahma
In this study, a facile and energy-efficient technique known as plasma-liquid interaction is employed for crystal growth, defect engineering, and band gap tuning. Using this novel procedure that minimizes the use of chemicals, cubic fluorite CeO2 nanoparticles are produced. The cubic fluorite structure of the prepared nanoparticles is confirmed by the Rietveld refinement method of XRD patterns. The further crystallization of cubic CeO2 nanoparticles (CeO2@300) is observed due to heat treatment following plasma interactions. However, prolonged plasma treatment led to the formation of crystallinity with the generation of oxygen-related vacancies in the host lattice. Post-heat treatment of the materials resulted in increased crystallinity and reduction in vacancies within the host matrix, as confirmed by the vacancy concentration calculations derived from XRD data and the variations of Raman absorption band intensity at 1047.24 cm−1. X-ray photoelectron spectroscopy analysis of the CeO2@RT sample reveals the presence of the Ce3+ ions, indicating the existence of vacancies. TEM analysis showed a good agreement with XRD analysis, revealing a polycrystalline in nature with the particle size distribution ranging from 3 nm to 10 nm. The calculated vacancy concentration indicated a higher vacancy concentration in the CeO2@RT sample, which is further confirmed by Raman spectral analysis. The characteristic vibrations of the Ce-O functional groups are identified using FTIR at absorption bands ranging from 814 cm−1 to 530 cm−1, supporting the cubic fluorite structure of the CeO2 nanoparticles. The band gap energy and defect energy, calculated from the UV–vis spectrum, reveal a lower band gap energy with higher defect energy for CeO2@RT sample, and higher band gap energy with lower defect energy for CeO2@300, making these material suitable for optoelectronic devices.
{"title":"Facile synthesis of CeO2 nanoparticles through plasma-liquid interaction","authors":"R. Basumatary , P. Kalita , H. Bailung , R. Brahma","doi":"10.1016/j.mtla.2025.102367","DOIUrl":"10.1016/j.mtla.2025.102367","url":null,"abstract":"<div><div>In this study, a facile and energy-efficient technique known as plasma-liquid interaction is employed for crystal growth, defect engineering, and band gap tuning. Using this novel procedure that minimizes the use of chemicals, cubic fluorite CeO<sub>2</sub> nanoparticles are produced. The cubic fluorite structure of the prepared nanoparticles is confirmed by the Rietveld refinement method of XRD patterns. The further crystallization of cubic CeO<sub>2</sub> nanoparticles (CeO<sub>2</sub>@300) is observed due to heat treatment following plasma interactions. However, prolonged plasma treatment led to the formation of crystallinity with the generation of oxygen-related vacancies in the host lattice. Post-heat treatment of the materials resulted in increased crystallinity and reduction in vacancies within the host matrix, as confirmed by the vacancy concentration calculations derived from XRD data and the variations of Raman absorption band intensity at 1047.24 cm<sup>−1</sup>. X-ray photoelectron spectroscopy analysis of the CeO<sub>2</sub>@RT sample reveals the presence of the Ce<sup>3+</sup> ions, indicating the existence of vacancies. TEM analysis showed a good agreement with XRD analysis, revealing a polycrystalline in nature with the particle size distribution ranging from 3 nm to 10 nm. The calculated vacancy concentration indicated a higher vacancy concentration in the CeO<sub>2</sub>@RT sample, which is further confirmed by Raman spectral analysis. The characteristic vibrations of the Ce-O functional groups are identified using FTIR at absorption bands ranging from 814 cm<sup>−1</sup> to 530 cm<sup>−1</sup>, supporting the cubic fluorite structure of the CeO<sub>2</sub> nanoparticles. The band gap energy and defect energy, calculated from the UV–vis spectrum, reveal a lower band gap energy with higher defect energy for CeO<sub>2</sub>@RT sample, and higher band gap energy with lower defect energy for CeO<sub>2</sub>@300, making these material suitable for optoelectronic devices.</div></div>","PeriodicalId":47623,"journal":{"name":"Materialia","volume":"39 ","pages":"Article 102367"},"PeriodicalIF":3.0,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143419598","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-06DOI: 10.1016/j.mtla.2025.102365
Mohammad Rezayat , Miguel Morales , Esmaeil Ghadiri Zahrani , Mahmoud Moradi , Bahman Azarhoushang , Antonio Mateo
Laser Surface Texturing (LST) has recently emerged as a corrosion mitigation strategy for materials in contact with high-temperature molten salts used in the next-generation Concentrated Solar Power (CSP) technology. Some issues related to the LST parameters, which may affect the corrosion resistance, have not been addressed yet. Therefore, the present work is focused on the effect of laser input density and pass repetitions for improving the corrosion resistance in molten carbonate salts of AISI 301LN stainless steel. The textured surface produced by a nanosecond laser and the oxide scales formed during subsequent corrosion tests in a molten salt mixture of Li2CO3Na2CO3-K2CO3 at 600 °C were analysed by complementary analytical and microscopy techniques. The results showed that the treated-surface samples at high laser power presented a strong decrease in corrosion rate, as compared with the as-received sample. This is attributed to the formation of a thicker and denser protective oxide scale. However, high laser power increased the susceptibility to corrosion at the heat-affected zone (HAZ). It could be effectively prevented with the accumulation of laser repetition passes, offering a new potential approach to maximize the enhancement of corrosion resistance using LST in the design of components for next-generation CSP plants.
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