Papers by Keyword: Spinodal Decomposition

Abstract: To pinpoint the relationship between the microstructure and corrosion resistance of the B10 copper tube, the copper tubes were annealed at 780°C and 810°C, respectively. Then the simulated seawater full immersion experiment was conducted. The corrosion film, grain size, boundary characteristics, and intragranular microstructure of the alloy were analyzed by OM, SEM, EBSD, and TEM. The results implied that the corrosion rate of the 810°C annealed copper tube is about 0.028 mm/a, which is 1.9 times that of the 780°C annealed copper tube. The average grain size of 810°C annealed copper tube is about 38.85 μm and the low ΣCSL account for 64.8 %, which is 1.5 times and 1.4 times that of 780°C annealed copper tube, respectively. There is a complete spinodal decomposition structure within the grain in an 810°C annealed copper tube, but there is an incomplete spinodal decomposition structure in a 780°C annealed copper tube. Theoretical analysis indicated that the large-sized grain clusters could be formed by numerous low-layer fault energy twin boundaries Σ3, and low ΣCSL combination Σ3, Σ9, Σ27, which can block the large crystal boundaries network, inhibit the phase precipitation and prevent invading of corrosive elements along the large crystal boundaries. The intragranular spinodal decomposition structure can improve the strength and toughness of the B10 copper tube, reduce the initiation of surface microcracks during service, and thus reduce pitting and crevice corrosion.

Abstract: This study leverages artificial intelligence (AI) to advance materials science, focusing on microstructural evolution in binary alloys during spinodal decomposition. Following the formulation of Zhu et al., we explore the microstructure evolution during interface-controlled spinodal decomposition. A comprehensive dataset captures the dynamic microstructural changes, highlighting the model's efficiency in analyzing complex data. The innovative use of an Autoencoder- ConvLSTM model enables precise, low-error microstructural transformation predictions, demonstrating AI’s potential in materials science research. This work provides a deeper understanding of material behaviors and offers new research directions.

Abstract: Copper-Nickel-Tin alloys have been recently developed by Hardening due to spinodal decomposition. The (Cu - 9Ni - 6Sn) system has shown promise in this direction and has been used to develop several high strength compositions. It is well known the fact that small element additions significantly modify phase transformation characteristics, the effect of adding Silicon or Silver on the Spinodal hardening in (Cu - 9Ni - 6Sn) alloy was studies close to the Spinodal cusp temperature. The presence of Silver also increased the ductility of alloy at the expense of some hardness. The effects of trace elements additions have been observed in this work with a view to improve high strength alloys as substitutes to the Copper – Beryllium alloys. The results obtained from the current research proved that adding a small amount of alloying elements with a percentage (1%) of silicon or silver to the base alloy (Cu - 9% Ni - 6% Sn), led to the stability of the mechanical properties resulting from the stability of the microstructure due to Heat treatment for hardening (Spinodal decomposition).

Abstract: Due to its high strength, excellent electrical conductivity and high resistance to stress corrosion, Cu-Ni-Sn alloy has been selected as a kind of advanced metal material which can be used as the manufacture of springs, connectors, bearings and so on. In addition, the addition of Nb can efficiently improve the comprehensive properties of the alloy. In the present work, the effect of heat treatment conditions on microstructure and mechanical properties were studied in a Cu-9Ni-6Sn-0.22Nb alloy by means of optical microscopy (OM), transmission electron microscopy (TEM), tensile test and microhardness tests. The results show that before ageing, a large number of fine γ precipitates with DO₂₂ type structure are distributed on the matrix. With the prolongation of ageing time, the ultimate tensile strength (UTS), yield strength (YS) and Vickers hardness increased firstly, and then decline. The reason can be attributed to the occurrence of spinodal decomposition and the formation of discontinuous precipitation (DP). At first, spinodal decomposition induced the enhanced interaction between dislocations and internal stress field, resulting in an increase of mechanical properties. Then the increased DP at grain boundaries leads to the decline of strength in the material. Finally, the relationship between the microstructure and the electrical conductivity was also analyzed, and the results show that the electrical conductivity increased with ageing time/ageing temperature increasing for the present alloy. Through the analysis of Matthiessen’ s rule, the variation of electrical resistivity depends on precipitates, solute atoms, dislocations, vacancies and grain boundaries, and the precipitates play an important role among them. Besides, more precipitates improve electrical conductivity. Therefore, the increase of ageing time/ageing temperature induced the increase of DP, resulting in an increase of electrical conductivity.

Abstract: The microstructural evolution in Cu-1.5 wt % Ti alloy aged at 400 °C was investigated by high resolution electron microscopy (HREM). The hardness and electrical conductivity of this alloy have been also characterized. The electron metallographic results showed that the sequence of the decomposition in the studied Cu-1.5 wt % Ti alloy can be summarized as follows: a modulated structure resulting from spinodal clustering → formation of clusters and then ordered fcc phase → formation of LRO β’-Cu₄Ti which distributed periodically along the <100>_Cu directions. The ordered fcc phase showed a cube-on-cube OR with matrix, while the LRO β’-Cu₄Ti showed an orientation relationship of [001]_Cu//[001]_β’ and (310)_Cu//(100)_β’. After aging for 24 h, the hardness and electrical conductivity of this alloy reached 175 HV and 25.3 % IACS, respectively. The spinodal clustering is responsible for the hardening of the alloy during the initial 30 min aging. The ordered fcc phase and β’-Cu₄Ti phase makes a significant contribution to the strengthening of the alloy during the advanced stage of aging.

Abstract: The addition of oxygen or nitrogen in titanium alloys increases the hardness by the solid solution strengthening. Spinodal decomposition in titanium alloys is also the way to increase the hardness. This study aimed to reveal the effect of oxygen or nitrogen addition on spinodal decomposition in Ti-10at%V. Ti-10at%V-(0, 1, 3)at%O or N alloys were prepared by arc-melting. They were solution-treated at 1200 or 1300 °C for 0.6 ks and then quenched in iced brine. The solution treated specimens were aged at 375 °C. The increase of hardness was decreased by the oxygen or nitrogen addition in the alloys. The addition of nitrogen more suppressed the age-hardening than the case of oxygen addition. The modulated structure caused by spinodal decomposition in the laths was observed in all the aged specimens. The wavelength of spinodal decomposition of the aged specimens increased with the addition of oxygen or nitrogen, leading to a decrease in age-hardening by spinodal decomposition.

Abstract: High strength elastic alloy has an important role in the manufacture of electrical equipment and machine building. Along with the development of information and telecommunications technology, the application of this alloy in electrical and electronic equipment is very increasingly. Even on boards or connectors of common electrical equipment such as computers, cell phones, these connectors are usually made of high strength elastic copper alloy. The design required features are small, precision built, with high mechanical strength and elasticity, heat resistance, abrasion and corrosion resistance in the operating environment to ensure its/the power and signal stability for a long time. The design trend is reduced in size but still assure the equipment quality is growing significantly and the corporation to manufacture equipment is researched thoroughly. Accordingly, this article presents the research results about the alloy copper with 9%Ni and 6%Sn which has the high elastic strength and elasticity properties of elastomers after heat treatment. The properties of the microstructure, hardness, conductivity, dry friction coefficient, the corrosion resistance of the alloy from which to determine the parameters for the materials selection procedure and the design of the manufacturing of magnetic contact of this alloy. The results of the study show that after heat treatment and deformation, the Cu-9Ni-6Sn has a strength of alloy up to 1200MPa, the elastic limit is 1100MPa and the conductivity is 8.4%IACS, respectively. The values ​​of this characteristic are consistent with the working conditions of the electrical contact. With the deformation process combined with the heat treatment process, the results of our research group created a single-phase homogeneous microstructure that is chemically stable with the spinodal decomposition in appropriate to the treatment of aging process. By modern methods, this paper demonstrates the durability of the alloy due to the spinodal decomposition during aging treatment at 350°C. This structure of spinodal decomposition is about 20-40nm in size, dispersed throughout the entire cross-section of the sample.

Abstract: For revealing internal atomic processes in bimetallic nanoparticles, individual hemispherical Ag-Cu alloy particles were grown by direct current (DC) magnetron sputtering. Phase separation of particles was found to be size- and composition-dependent. Particles smaller than 5 nm in diameter remained as a solid solution of the components for all tested compositions (15-80 at.% Ag). At 15 and 30 at.% Ag compositions phase separation was observed only for particles above 5 nm in diameter. Computer simulations by Stochastic Kinetic Mean Field model reproduced the size-dependence of the decomposition and the internal structure of two-phase particles. Theoretical explanation is given for the composition dependence of the phase separation tendency.

Abstract: It is well known that when duplex stainless steels (DSS) are subjected to temperatures ranging from 300 to 1000 °C they may undergo precipitation of several phases, which can seriously impair their mechanical properties and corrosion resistance. The present work studied the effect of thermal aging (up to 2000 h) at 475 °C on the corrosion and mechanical properties of the newly developed 2404 DSS. The evaluation was based on potentiodynamic polarization in 3.5% NaCl solution and on Charpy tests. The pitting corrosion resistance was found to decrease significantly with aging time at 475 °C. In addition, Charpy tests revealed that after 100 h of thermal aging the material becomes brittle due to the spinodal decomposition of ferrite.

Abstract: This paper presents the effect of deformation on the change of microstructure of Cu-15Ni-8Sn and Cu-9Ni-6Sn alloy during heat treatment. The samples were homogenized, quenched, cold-rolled at different thickness reduction, and aged. The effects of deformation on microstructures were observed by optical microscope and SEM. The spinodal decomposition after homogenized solid solution, deformation and aging of these alloys was observed. The results have shown that during aging, from the rich-tin zones formed by spinodal decomposition, produced phase γ. The microstructure included of α +γ. The deformation accelerated the aging process and rapid increased the diameter of formed phase γ.