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预退火时间对Pd40Cu30Ni10P20玻璃转变及晶化的影响 总被引:3,自引:0,他引:3
采用示差扫描量热(DSC)分析方法,测定了大块非晶合金Pd40Cu30Ni10P20经523 K((Tg-100 K)<7<Tg)不同时间(0~64 h)预退火后的玻璃转变温度7g、玻璃转变峰温度TM、起始晶化温度Tx、晶化峰的峰温Tp、晶化焓以及在玻璃转变过程中的比热容增量,并根据Kissinger公式计算了晶化的表观活化能.同时,测量了不同时间预退火后样品的显微硬度.结果表明:在玻璃转变温度以下的预退火处理使Pd40Cu30Ni10P20大块非晶合金的微观原子组态发生变化,从而影响了其随后的玻璃转变行为,但对晶化的影响不大.其显微硬度随预退火时间的延长而逐步增加后趋于稳定.并利用结构弛豫理论分析了预退火对玻璃转变、晶化和显微硬度的影响. 相似文献
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Employing isothermal and isochronal differential scanning calorimetry, an analytical phase transformation model was used to study the kinetics of crystallization of amorphous Mg82.3Cu17.7 and Pd40Cu30P20Ni10 alloys. The analytical model comprised different combinations of various nucleation and growth mechanisms for a single transformation. Applying different combinations of nucleation and growth mechanisms, the nucleation and growth modes and the corresponding kinetic and thermodynamic parameters, have been determined. The influence of isothermal pre-annealing on subsequent isochronal crystallization kinetics with the increase of pre-annealing can be analyzed. The results show that the changes of the growth exponent, n, and the effective overall activation energy Q, occurring as function of the degree of transformation, do not necessarily imply a change of nucleation and growth mechanisms, i.e. such changes can occur while the transformation is isokinetic. 相似文献
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镍基块状非晶合金的晶化动力学行为 总被引:4,自引:0,他引:4
利用铜模铸造方法制备了Ni45 Ti23Zr15Si5Pd12块状非晶合金,采用扫描差热分析(DSC)和X射线衍射(XRD)对该块状非晶合金的晶化动力学行为进行了研究.结果表明:Ni45Ti23Zr15Si5Pd12块状非晶样品的晶化过程为多阶段晶化,主要晶化过程的Avrami指数大于3.0,为三维形核长大过程;随着晶化体积分数的增加,剩余非晶的晶化激活能增大,合金热稳定性增加;原子尺寸差异以及各原子间大的负混合焓是合金具有高的热稳定性的主要原因. 相似文献
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Structure relaxation and crystallization of Al83Ni10Ce7 metallic glass were studied by different scanning calorimetry (DSC) and X-ray diffraction (XRD). According to the DSC scan, it is interesting to find that the second exothermic peak changes with pre-annealing temperatures (below glass transition temperature), suggesting a change in the amorphous structure upon relaxation. Continuous heating crystallization and isothermal crystallization exhibit different crystallization mechanism of the present alloy. fcc-Al and a metastable phase precipitate simultaneously in the first stage crystallization during continuous heating; however, only a metastable phase precipitates during isothermal annealing below glass transition temperature (Tg). 相似文献
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THE CRYSTALLIZATION KINETICS OF AN AMORPHOUS Ti-RICH NiTi FILM 总被引:1,自引:0,他引:1
1. IntroductionIn recent years, many studies have been made on shape memory alloys (SMA) concentrating in its martensitic transformation, shape memory effect (SME) and superplasticity[1--4].SMA film is an excellent candidate of actuator for MEMS (microelectromechanic systems)because it is capable of generating high strain and force compared with other actuationmaterial used as mic.oactuators[5]. Now, the research on SMA film is mainly concentratedon Ni-Ti or Ni-Ti-X alloys, which posse… 相似文献
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高速连铸保护渣结晶特性的研究 总被引:7,自引:0,他引:7
对高速连铸保护渣中Li2O,MgO,Na2O,K2O,Al2O3t F^-对保护结晶特性的影响进行了实验研究和理论分析,结果表明,Li2O含量为2%时结晶温度,结晶率最低;碱度提高,使结晶温度提高,结晶率增大;随着Na2O的加入量增大,结晶温度降低,结晶率增大,在5%-11%范围内,提高MgO含量,保护渣的玻璃性得到改善,结晶矿物颗粒变小。 相似文献
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在Fe-Co-Nd-B非晶合金中添加4%的Nb(原子分数)可延迟其晶化过程, 提高晶化温度, 并使其热稳定性显著提高. Nb抑制Fe3B晶化相的形核, 但促进Fe23B6相的形核及长大. Nb可使晶化相的平均晶粒尺寸从30-60 nm减至14-20 nm. Nb使由初始晶化温度计算的晶化激活能明显降低. Fe-Co-Nd-B合金中, α-Fe(Co), Fe3B和Nd2(Fe, Co)14B晶化相的形核过程要难于长大过程, 而加Nb后α-Fe(Co), Fe23B6和Nd2(Fe, Co)14B晶化相的长大过程要难于形核过程, 但Nb基本未改变晶化相的形核及长大机制. 非晶合金的晶化主要是一维界面控制的形核以及形核率随时间减小的三维长大过程. 相似文献
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H. P. Tang J. Ma J. Z. Wang C. L. Li 《JOM Journal of the Minerals, Metals and Materials Society》2017,69(4):645-650
Stainless steel fiber felt is a class of unique porous metal materials. This study investigates the effect of pre-annealing on the sintering of stainless steel fiber felt through quantitative characterization of sintered joints based on synchrotron radiation experiments. The sintered joint size was found to follow a marked normal distribution in fiber felt samples sintered with and without pre-annealing. However, pre-annealing prior to sintering led to a significant reduction in the total number of sintered joints as well as a reduction in the percentage of large sintered joints. Consequently, fiber felt samples sintered with pre-annealing achieved less than half the tensile strength of those sintered without pre-annealing. Delamination through fracture of sintered joints was pronounced in fiber felt samples sintered with pre-annealing, while failure occurred mainly through fracture of individual fibers in those sintered without pre-annealing. It was concluded that sintering without pre-annealing is necessary for the fabrication of high-strength fiber felt products and the reasons are briefly discussed. 相似文献
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MIAO Weifang WANG Jingtang LI Shuling Institute of Metal Research Academia Sinica Shenyang China 《金属学报(英文版)》1991,4(7):26-30
The crystallization kinetics of the Cu_(40)Ti_(60) glasses,either as-quenched or pre-annealed,hasbeen studied by differential scanning calorimetry.The crystallization temperature,activationenergy for crystallization and Avrami exponent were found to be lowered by the pre-an-nealing.Both activation energies of nucleation and growth of the amorphous CuaoTi_(60) are ob-tained on the basis of experimental results and theoretical analysis. 相似文献
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CRYSTALLIZATIONOFTHEBORONCOMPONENTBEARINGMgO-B_2O_3-SiO_2SLAGZhangPeixin;GuoZhenzhong;LinHong;SuiZhitong(DepartmentofNonferrou?.. 相似文献
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在Ni-P基化学沉积液中加入氯化钴,得到Ni-Co-P合金镀层,与Ni-P镀层相比较其性能得以改善。研究了氯化钴对化学沉积所起的作用及其影响机制,结果表明:加入适量的CoCl2可有效提高镀层的硬度和耐热溶液腐蚀性能,并能抑制镀层的晶化,提高其晶化温度。 相似文献
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