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Mg-6Zn-1Mn镁合金中MgZn相析出的热力学计算 总被引:2,自引:0,他引:2
以Miedema生成热模型和Toop模型为基础,参考三元合金溶体中金属间化合物析出行为的热力学模型,计算Mg-6Zn-1Mn(质量分数,下同)三元合金体系中Mg和Zn的活度,进而求出重要强化相MgZn析出反应的Gibbs自由能变化与温度的关系,并得出其析出温度为580 K.MgZn析出温度的计算结果与该合金所取均匀化处理温度相符,并得到了热分析实验的进一步验证. 相似文献
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Ag/CuO复合材料反应合成热力学分析 总被引:1,自引:0,他引:1
通过对Ag/CuO复合材料在反应合成制备中各元素、亚金属氧化物与1 mol氧气反应生成金属氧化物的标准自由焓的热力学计算,绘制了标准自由焓与温度关系图;考虑到氧压力对反应进行有重要影响,在标准自由焓与温度关系图中绘制了氧压力随温度变化的直线.结果表明:Ag与O_2,Cu_2O与O_2的反应是一种可逆反应,其发生可逆转变的温度分别为586.818,667.663 K;氧的压力对金属氧化物的分解有重要影响:压力越低,金属氧化物越易分解;并通过热力学分析结果,最终确定了Ag/CuO复合材料反应合成烧结工艺. 相似文献
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《中国有色金属学会会刊》2015,(5)
为研究铁水中钛元素碳热还原反应规律,提供高炉护炉理论依据,利用高温熔炼、急速淬火、化学分析以及热力学模型计算等方法,在实验室条件下利用分析纯试剂研究在1350~1600°C间钛在低钛渣系CaO-SiO2-MgO-Al2O3-TiO2与铁水间的分配行为。研究结果表明,随着反应温度的增加,钛的分配比L(Ti)增加,但系统活度系数γsys降低,从而导致反应平衡常数升高。结合Wagner与凝聚电子相模型,通过对实验数据进行拟合,得到钛碳热还原反应的吉布斯自由能公式。最后,结合实验所得结果,给出了高炉铁水中w(Si)与w(Ti)含量的关系以及可以达到护炉效果的最小入炉钛负荷。 相似文献
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《组合机床与自动化加工技术》2020,(7)
不同的转速会导致滚珠丝杠系统产生不同的温度变化。分析滚珠丝杠副转速和温升的关系,建立了滚珠丝杠副热传递过程的微分方程,得到了滚珠丝杠副使用过程中的温度随时间变化的表达形式。进一步得到热平衡状态时滚珠丝杠副的温升计算方法。为验证该方法的有效性,对该模型计算得到的理论温升值与不同转速下试验得到的实际温升值进行对比。通过滚珠丝杠副综合性能试验装置,完成不同转速下滚珠丝杠副温升的测量试验,实际温升值与理论温升值的差值10%以内,证明该方法能很好地预测滚珠丝杠副的温升。 相似文献
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氧化铝碳热还原反应机制及其热力学 总被引:3,自引:0,他引:3
研究了球磨活化后氧化铝碳热还原反应合成氮化铝的机理 ,提出了通过氧化铝碳热还原反应合成氮化铝的新机制 :氧化铝首先发生氮化反应生成AlON相 ,AlON再还原氮化生成氮化铝。通过热力学计算得到的反应平衡温度与实验得到的氮化铝开始生成温度相吻合。 相似文献
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采用Gleeble3500热模拟实验机在900~1100℃温度、0.01~10s-1应变速率条件下,对超高强度钢Aer Met100进行了热压缩实验,得到了该合金的真应力-真应变曲线。利用Jonas双曲函数模型建立了峰值应力与变形温度和应变速率的关系,确定了材料的激活能为261.2 k J/mol,应变速率敏感系数m=0.0998,温度敏感系数s=7912。通过一元线性回归法获得了不同应变量下的参数值,得到了上述条件下受到等效应变影响的流动应力本构关系模型,该模型计算相对误差小于11.3%。 相似文献
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自蔓延高温合成TiC-Ni金属陶瓷的热力学编程计算与分析 总被引:2,自引:0,他引:2
根据热力学原理对Ti、C、Ni三元体系进行热力学编程计算,绘出了标准反应自由焓随温度变化的曲线、绝热温度随Ni含量变化的曲线以及绝热温度随预热温度变化的曲线,通过对曲线进行分析认为:Ti、C、Ni三元体系的主反应是Ti C=TiC;体系的绝热温度随Ni含量的增加而下降,当预热温度为600K时,最佳的理论Ni含量约40%;体系的绝热温度随预热温度的升高而升高,当Ni含量过大,体系的绝热温度小于1800K时,可以适当提高预热温度,来确保反应的自发进行。 相似文献
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采用数值模拟的方法,研究了纯铝在静高压作用下凝固过程温度场的变化情况。首先建立了温度场的数学模型,根据压力与金属熔点的关系,将压力作用到凝固过程的温度场上。模拟结果表明:压力越大,纯Al开始凝固的时间越早;在凝固过程中,压力越大,对应的温度变化速度越快。 相似文献
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X. J. Liu I. Ohnuma R. Kainuma K. Ishida 《Journal of Phase Equilibria and Diffusion》1999,20(1):45-56
A thermodynamic calculation of the Al-Mn binary system that takes into account recent experimental results and includes five
intermetallic compounds and all the solid-solution phases is presented. The Gibbs energy of the body-centered cubic (bcc)
phase has been described on the basis of the two-sublattice model that includes the second-order A2/B2 ordering reaction as well. A consistent set of optimized thermodynamic parameters has been arrived at for describing the
Gibbs energy of each phase in this system leading to a better fit between calculation and experiments. 相似文献
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A thermodynamic calculation of the Al-Mn binary system that takes into account recent experimental results and includes five intermetallic compounds and all the solid-solution phases is presented. The Gibbs energy of the body-centered cubic (bcc) phase has been described on the basis of the two-sublattice model that includes the second-order A2/B2 ordering reaction as well. A consistent set of optimized thermodynamic parameters has been arrived at for describing the Gibbs energy of each phase in this system leading to a better fit between calculation and experiments. 相似文献
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H. X. Liu C. P. Wang Y. Yu X. J. Liu Y. Takaku I. Ohnuma R. Kainuma K. Ishida 《Journal of Phase Equilibria and Diffusion》2012,33(1):9-19
This work first deals with the experimental investigation and thermodynamic calculation in the Al-Bi-Sn ternary system. The
phase equilibria at 400 and 500 °C in the Al-Bi-Sn ternary system have been experimentally determined by electron probe microanalysis
(EPMA) on the equilibrated alloys. Based on the experimental data determined in the present work, the phase equilibria in
the Al-Bi-Sn ternary system have been thermodynamically assessed by using the CALPHAD (CALculation of PHAse Diagrams) method,
and a consistent set of thermodynamic parameters leading to reasonable agreement between the calculated results and experimental
data was obtained. The additions of Sn can effectively reduce the stable liquid miscibility gap in the Al-Bi binary system
and gradually decrease its critical temperature. And the additions of Bi can significantly stabilize the metastable liquid
miscibility gap in the Al-Sn binary system. This is shown by an initial decrease in critical temperature with increasing Bi
additions. 相似文献
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Bing Yang 《Journal of Materials Engineering and Performance》2003,12(3):345-353
An IR (IR) thermography technique, as a nondestructive evaluation technique, was applied to investigate the fatigue damage
of reactor pressure vessel (RPV) steels during 20 Hz and 1000 Hz fatigue testing. Five stages of temperature profile were
observed: an initial increase of the average specimen temperature, a region of temperature decrease, an equilibrium (steady-state)
temperature region, an abrupt increase of the temperature, and a drop of temperature following specimen failure. The relationship
between the temperature, stress-strain state, and fatigue behavior is discussed. Both thermodynamic and heat-transfer theories
are applied to model the observed temperature variation during fatigue. The stress-strain state of the material has been back-calculated
from the observed temperature profiles. The predicted and measured temperature evolutions and mechanical behavior during fatigue
were found to be in good agreement. Thermography appears to provide a useful method of investigating the stress-strain behavior
during fatigue. 相似文献
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1 INTRODUCTIONThephenomenonthattheinterfaceoftwospeci menscontactundertheeffectofmechanicloadisseeneverywhere[1] ,whilewhatistheact 相似文献