The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Lipeng Ding - One of the best experts on this subject based on the ideXlab platform.
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effect of ag and cu additions on natural aging and Precipitation Hardening behavior in al mg si alloys
Journal of Alloys and Compounds, 2017Co-Authors: Yaoyao Weng, Lipeng DingAbstract:Abstract The effects of Ag and/or Cu additions on the natural aging and Precipitation Hardening behavior of Al-Mg-Si alloys were investigated by using hardness test, differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). Both Ag and Cu additions enhanced the Hardening kinetics of Al-Mg-Si alloys during natural aging (NA) and artificial aging (AA) treatments. The strong interaction of Cu, Ag and Mg atoms is responsible for the improved Precipitation kinetics of these alloys, resulting in a refinement of clusters and precipitates. The stronger interaction between Ag and Mg results in lower T4 hardness and higher AA hardness, compared to Cu. This is potentially beneficial for automobile applications where rapid Hardening during paint baking is required. Both Ag and Cu additions reduce the detrimental effect of NA on subsequent AA, due to the formation of Ag or Cu-containing clusters. The clear advantage of Ag addition, compared to Cu, is the improvement of Precipitation Hardening response of Al-Mg-Si alloys.
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effect of ag and cu additions on natural aging and Precipitation Hardening behavior in al mg si alloys
Journal of Alloys and Compounds, 2017Co-Authors: Yaoyao Weng, Lipeng DingAbstract:Abstract The effects of Ag and/or Cu additions on the natural aging and Precipitation Hardening behavior of Al-Mg-Si alloys were investigated by using hardness test, differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). Both Ag and Cu additions enhanced the Hardening kinetics of Al-Mg-Si alloys during natural aging (NA) and artificial aging (AA) treatments. The strong interaction of Cu, Ag and Mg atoms is responsible for the improved Precipitation kinetics of these alloys, resulting in a refinement of clusters and precipitates. The stronger interaction between Ag and Mg results in lower T4 hardness and higher AA hardness, compared to Cu. This is potentially beneficial for automobile applications where rapid Hardening during paint baking is required. Both Ag and Cu additions reduce the detrimental effect of NA on subsequent AA, due to the formation of Ag or Cu-containing clusters. The clear advantage of Ag addition, compared to Cu, is the improvement of Precipitation Hardening response of Al-Mg-Si alloys.
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the natural aging and Precipitation Hardening behaviour of al mg si cu alloys with different mg si ratios and cu additions
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2015Co-Authors: Lipeng Ding, Robert E Sanders, Zhiqing Zhang, Guang YangAbstract:Abstract The natural aging and artificial aging behaviours of Al-Mg-Si-Cu alloys with different Mg/Si ratios and Cu additions were investigated using Vickers microhardness measurements, differential scanning calorimetry (DSC) analysis and transmission electron microscopy (TEM) characterisation. Excess Si and Cu additions enhanced the alloy Hardening ability during natural (NA) and artificial aging (AA). Alloys with low Cu and high Si contents exhibited higher Precipitation Hardening than alloys rich in Mg during artificial aging. In contrast, the alloys with high amounts of Cu were less dependent on the Mg/Si ratio during Precipitation Hardening due to their similar aging kinetics. The main precipitate phases that contributed to the peak-aging hardness were the L, Q′ and β″ phases. In the over-aging conditions, the alloys rich in Mg and Cu had finer and more numerous precipitates than their Si-rich equivalents due to the preferential Precipitation of the L phase. The combination of excess Mg and high Cu resulted in an alloy with a relatively low hardness in T4 temper and a relatively higher hardness after the paint baking cycle. Thus, this alloy has good potential for use in auto body panel applications.
Hanshan Dong - One of the best experts on this subject based on the ideXlab platform.
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the corrosion and corrosion wear behaviour of plasma nitrided 17 4ph Precipitation Hardening stainless steel
Surface & Coatings Technology, 2007Co-Authors: M Esfandiari, Hanshan DongAbstract:Abstract Plasma surface nitriding of 17-4 PH martensitic Precipitation Hardening stainless steels was conducted at 350 °C, 420 °C and 500 °C for 10 h using a DC plasma nitriding unit, and the surface properties of the plasma surface engineered samples were systematically evaluated. Experimental results have shown that the surface properties of the plasma nitrided layers in terms of hardness, wear resistance, corrosion behaviour and corrosion–wear resistance are highly process condition dependent, and it is feasible to provide considerable improvement in wear, corrosion and corrosion–wear resistance of 17-4PH steel using optimised plasma treatment conditions. All three treatments can effectively improve the surface hardness and the sliding wear resistance under unlubricated conditions; high temperature (420 °C and 500 °C) treated materials revealed improved corrosion and corrosion–wear properties due to the formation of surface compound layers.
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the corrosion and corrosion wear behaviour of plasma nitrided 17 4ph Precipitation Hardening stainless steel
Surface & Coatings Technology, 2007Co-Authors: M Esfandiari, Hanshan DongAbstract:Abstract Plasma surface nitriding of 17-4 PH martensitic Precipitation Hardening stainless steels was conducted at 350 °C, 420 °C and 500 °C for 10 h using a DC plasma nitriding unit, and the surface properties of the plasma surface engineered samples were systematically evaluated. Experimental results have shown that the surface properties of the plasma nitrided layers in terms of hardness, wear resistance, corrosion behaviour and corrosion–wear resistance are highly process condition dependent, and it is feasible to provide considerable improvement in wear, corrosion and corrosion–wear resistance of 17-4PH steel using optimised plasma treatment conditions. All three treatments can effectively improve the surface hardness and the sliding wear resistance under unlubricated conditions; high temperature (420 °C and 500 °C) treated materials revealed improved corrosion and corrosion–wear properties due to the formation of surface compound layers.
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improving the surface properties of a286 Precipitation Hardening stainless steel by low temperature plasma nitriding
Surface & Coatings Technology, 2007Co-Authors: M Esfandiari, Hanshan DongAbstract:Abstract Plasma nitriding over a wide range of treatment temperatures between 350 and 500 °C and time from 5 to 30 h on A286 austenitic Precipitation-Hardening stainless steels has been investigated. Systematic materials characterisation of the plasma surface alloyed A286 alloy was carried out in terms of microstructure observations, phase identification, chemical composition depth profiling, surface and cross-section microhardness measurements, electrochemical corrosion tests, dry sliding wear tests and corrosion-wear tests. Experimental results have shown that plasma nitriding can significantly improve the hardness and wear resistance of A286 stainless steels owing to the formation of nitrogen supersaturated S-phase; the surface layer characteristics (e.g. microstructure, case depth and hardness) of the plasma surface alloyed cases are highly process condition dependent and there are possibilities to provide considerable improvement in wear, corrosion and corrosion-wear resistance of A286 steel.
Petar Ratchev - One of the best experts on this subject based on the ideXlab platform.
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Precipitation Hardening of an al 4 2 wt mg 0 6 wt cu alloy
Acta Materialia, 1998Co-Authors: Petar Ratchev, P. De Smet, Bert Verlinden, Paul Van HoutteAbstract:Abstract The Precipitation Hardening of an experimental Al–4.2 wt% Mg–0.6 wt% Cu alloy has been studied. After a first initial jump, the yield strength increases almost linearly with the logarithm of the ageing time and a peak of hardness is reached after 11 days at 180°C. Special attention is given to the Precipitation Hardening during the early stage of ageing. It has been shown that S″ phase can be formed heterogeneously on dislocation loops and helices and a new mechanism of Precipitation Hardening due to this S″ phase Precipitation is proposed. The Precipitation of S″ on dislocations is the predominant cause of strengthening during the initial stage of Precipitation Hardening (up to 30 min at 180°C). Guinier–Preston–Bagaryatsky (GPB) zones (or better, the recently introduced “Cu/Mg clusters”) also appear in the initial stage, but their contribution to the hardness, which up to now was considered to be predominant, is shown to be smaller then the one of the S″ precipitates. Since the density of the S″ nucleation sites is related to the amount of dislocations, this mechanism is important in the case of a bake Hardening treatment when ageing is preceded by cold deformation. Uniform S″ Precipitation has also been found at the later ageing stage, which suggests that the contribution of S″ to the Precipitation Hardening at that stage is not less important.
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Precipitation Hardening of anal 4 2 wt mg 0 6 wt cu alloy
Acta Materialia, 1998Co-Authors: Petar Ratchev, P. De Smet, Bert Verlinden, P Van HoutteAbstract:Abstract The Precipitation Hardening of an experimental Al–4.2 wt% Mg–0.6 wt% Cu alloy has been studied. After a first initial jump, the yield strength increases almost linearly with the logarithm of the ageing time and a peak of hardness is reached after 11 days at 180°C. Special attention is given to the Precipitation Hardening during the early stage of ageing. It has been shown that S″ phase can be formed heterogeneously on dislocation loops and helices and a new mechanism of Precipitation Hardening due to this S″ phase Precipitation is proposed. The Precipitation of S″ on dislocations is the predominant cause of strengthening during the initial stage of Precipitation Hardening (up to 30 min at 180°C). Guinier–Preston–Bagaryatsky (GPB) zones (or better, the recently introduced “Cu/Mg clusters”) also appear in the initial stage, but their contribution to the hardness, which up to now was considered to be predominant, is shown to be smaller then the one of the S″ precipitates. Since the density of the S″ nucleation sites is related to the amount of dislocations, this mechanism is important in the case of a bake Hardening treatment when ageing is preceded by cold deformation. Uniform S″ Precipitation has also been found at the later ageing stage, which suggests that the contribution of S″ to the Precipitation Hardening at that stage is not less important.
Shahrzad Esmaeili - One of the best experts on this subject based on the ideXlab platform.
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modeling of Precipitation Hardening for the naturally aged al mg si cu alloy aa6111
Acta Materialia, 2003Co-Authors: Shahrzad Esmaeili, D J Lloyd, Warren J. PooleAbstract:The effect of natural aging on the artificial aging behavior of the Al-Mg-Si-Cu alloy AA6111 is examined by isothermal calorimetry and the results are analyzed in a new kinetic model. The model describes the kinetics of concurrent precipitate formation and cluster dissolution during artificial aging of the alloy with variable levels of natural aging. The kinetic model is then combined with a recently developed yield strength model for AA6111 to predict the Precipitation Hardening behavior of the naturally aged alloy. The validity of both models is verified by agreement between the predictions of the models and independent experimental results.
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on the Precipitation Hardening behavior of the al mg si cu alloy aa6111
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2003Co-Authors: Shahrzad Esmaeili, D J Lloyd, Xiang Wang, Warren J. PooleAbstract:The Precipitation-Hardening behavior of aluminum alloy AA6111 during artificial aging and the influence of prior natural aging on the aging behavior were investigated. The evolution of microstructure was studied using quantitative transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The evolution of the relative volume fraction of precipitates for the solution-treated alloy was determined using isothermal calorimetry and a new analysis based on the DSC technique. Quantitative TEM was also used to obtain the rate of Precipitation of microscopically resolvable phases during aging at 180 °C. Three types of precipitates, i.e., unresolved Guinier-Preston (GP) zones, β″, and Q′, were found to form during aging at 180 °C. The evolution of yield strength was related to the evolution of microstructure. It was found that the high Hardening rate during artificial aging for the solution-treated alloy is due to the rapid Precipitation of the β″ phase. Natural aging prior to artificial aging was found to decrease the rate of Precipitation of β″. The slow Hardening rate for the naturally aged alloy was attributed to the slower nucleation and growth of β″ phase.
M Esfandiari - One of the best experts on this subject based on the ideXlab platform.
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the corrosion and corrosion wear behaviour of plasma nitrided 17 4ph Precipitation Hardening stainless steel
Surface & Coatings Technology, 2007Co-Authors: M Esfandiari, Hanshan DongAbstract:Abstract Plasma surface nitriding of 17-4 PH martensitic Precipitation Hardening stainless steels was conducted at 350 °C, 420 °C and 500 °C for 10 h using a DC plasma nitriding unit, and the surface properties of the plasma surface engineered samples were systematically evaluated. Experimental results have shown that the surface properties of the plasma nitrided layers in terms of hardness, wear resistance, corrosion behaviour and corrosion–wear resistance are highly process condition dependent, and it is feasible to provide considerable improvement in wear, corrosion and corrosion–wear resistance of 17-4PH steel using optimised plasma treatment conditions. All three treatments can effectively improve the surface hardness and the sliding wear resistance under unlubricated conditions; high temperature (420 °C and 500 °C) treated materials revealed improved corrosion and corrosion–wear properties due to the formation of surface compound layers.
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the corrosion and corrosion wear behaviour of plasma nitrided 17 4ph Precipitation Hardening stainless steel
Surface & Coatings Technology, 2007Co-Authors: M Esfandiari, Hanshan DongAbstract:Abstract Plasma surface nitriding of 17-4 PH martensitic Precipitation Hardening stainless steels was conducted at 350 °C, 420 °C and 500 °C for 10 h using a DC plasma nitriding unit, and the surface properties of the plasma surface engineered samples were systematically evaluated. Experimental results have shown that the surface properties of the plasma nitrided layers in terms of hardness, wear resistance, corrosion behaviour and corrosion–wear resistance are highly process condition dependent, and it is feasible to provide considerable improvement in wear, corrosion and corrosion–wear resistance of 17-4PH steel using optimised plasma treatment conditions. All three treatments can effectively improve the surface hardness and the sliding wear resistance under unlubricated conditions; high temperature (420 °C and 500 °C) treated materials revealed improved corrosion and corrosion–wear properties due to the formation of surface compound layers.
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improving the surface properties of a286 Precipitation Hardening stainless steel by low temperature plasma nitriding
Surface & Coatings Technology, 2007Co-Authors: M Esfandiari, Hanshan DongAbstract:Abstract Plasma nitriding over a wide range of treatment temperatures between 350 and 500 °C and time from 5 to 30 h on A286 austenitic Precipitation-Hardening stainless steels has been investigated. Systematic materials characterisation of the plasma surface alloyed A286 alloy was carried out in terms of microstructure observations, phase identification, chemical composition depth profiling, surface and cross-section microhardness measurements, electrochemical corrosion tests, dry sliding wear tests and corrosion-wear tests. Experimental results have shown that plasma nitriding can significantly improve the hardness and wear resistance of A286 stainless steels owing to the formation of nitrogen supersaturated S-phase; the surface layer characteristics (e.g. microstructure, case depth and hardness) of the plasma surface alloyed cases are highly process condition dependent and there are possibilities to provide considerable improvement in wear, corrosion and corrosion-wear resistance of A286 steel.
