新型镍基粉末高温合金动态再结晶的数学模型

采用Gleeble 15 0 0热模拟试验机对新型镍基粉末高温合金在 10 70℃～ 1170℃ ,应变速率为 5× 10 - 4s- 1～2× 10 - 1s- 1的条件下进行了轴向压缩试验。通过加工硬化率和应变的关系曲线确定稳态应变εs,并绘制了该合金的动态再结晶图。结果表明 ,Zener Hollomon参数变化对动态再结晶的临界应变量影响较小 ,对稳态应变量影响较大 ,并建立了该合金的动态再结晶动力学模型和晶粒尺寸模型     

Thixoforming of SiC ceramic matrix composites in pseudo-semi-solid state

1INTRODUCTIONIt has great economic profit to exploit the uti-lization of SiC ceramic material for its strength,hardness,wear resistance,corrosion resistanceand high temperature resistance,abundant re-source and low price.But the brittle charactergreatly restricts its application in the field of engi-neering structure materials.Recently a series ofceramic matrix composites with exi mious perform-ance have been developed by reinforcing the matrixmaterial with other materials.Al/SiC is a la…     

共轭环填料性能研究及测试方法改进[摘]

本文总结了我国自行开发的高效散堆填料——共轭环的流体力学与传质性能,全面论述了共轭环的结构特点。用φ38塑料共轭环、鲍尔环、一阶梯环做对比实验结果:共辘环每米压强降比阶梯环低40~45%,比鲍尔环低50~55%;共辘环的传质单元高度比阶梯环低15%,比鲍尔环低     

高效塔填料——共轭环的性能研究

本文总结了我国自行开发的高效散堆填料——共轭环的流体力学与传质性能,论述了共轭环的结构特点.用φ38塑料共轭环、鲍尔环、阶梯环做对比实验,其结果为:共轭环的每米压强降比阶梯环低40-45%、比鲍尔环低50—55%,共轭环的传质单元高度比阶梯环低15%、比鲍尔环低30%,即共轭环的流体力学和传质性能均比阶梯环、鲍尔环优良.     

Effect of Zr content on quench sensitivity of AlZnMgCu alloys

The effect of Zr content on quench sensitivity of AlZnMgCu alloys was investigated by mechanical properties testing and microstructure observations. The results show that with the increase of Zr the quench sensitivity relative to hardness and strength increases, while that relative to elongation decreases. From hardness and strength viewpoints, the low quench sensitivity is observed for the Zr-free and 0.05% Zr-containing alloys, which is quite quench sensitive from the ductility viewpoint. The largest quench sensitivity relative to hardness and strength is observed for 0.1% Zr-containing alloy, this is mainly due to large amount of high angle grain boundaries and incoherent Al3Zr dispersoids caused by recrystallization, which may efficiently promote heterogeneous precipitation during air quenching. More than 0.05% Zr can significantly decrease the quench sensitivity relative to ductility, which can be primarily attributed to recrystallization inhibiting and grain refining effects of Zr.     

Mechanism of strengthening of cube texture for high purity aluminum foils by additional-annealing

1　INTRODUCTIONHighpurityaluminumfoilsareusedastheanodematerialofhighvoltageelectrolyticcapacitorswhichneedstrongcubetexture { 0 0 1}〈10 0〉forlargeeffec tivesurfacefromchanneletching[1] .Becauseofitstechnicalimportance ,alotofeffortshavebeenmadetodevelopstrongcubetextureinhigh purityalu minumfoils[2 8] .Itwasfoundthatthecubetextureinthefoilscanbestrengthenedviaanannealingpro cessfollowedbyalowcoldrolling[7,8] ,andsuchanannealingiscalledadditional annealinginthispaper .Buttherewerefewinv…     

淬火速率对AlZnMgCu(Zr)合金断裂行为的影响

通过室温力学性能测试,光学显微镜、扫描电镜和透射电镜研究了淬火速率对AlZnMgCu(Zr)合金断裂行为的影响.结果表明:含Zr小于0.1%合金随着淬火速率的降低,由穿晶破断和沿晶开裂的混合型断裂逐渐转变成沿晶断裂;其主要原因是淬火速率降低使晶界无沉淀析出带(PFZ)宽化.含Zr大于等于0.1%的合金随着淬火速率的降低由穿晶破断为主的断裂逐渐转变成沿晶开裂和穿晶剪切的混合型断裂;沿晶断裂的产生主要是由于晶界无沉淀析出带宽化;穿晶剪切主要是由于慢速淬火过程中晶粒内部析出了大量粗大的η平衡相.     

固溶后预析出对7A55铝合金力学及腐蚀性能的影响

采用硬度测试、电导率测试及透射电镜观察，研究固溶后降温至440℃预析出处理时间对7A55铝合金板材力学和腐蚀性能的影响。结果表明：随预析出处理时间的延长，基体析出相逐渐增多且长大，导致合金时效后硬度和强度先提高而后降低；晶界析出相逐渐长大，晶界无沉淀析出带宽化，晶界相不连续性先提高而后降低，导致合金抗晶问腐蚀和剥落腐蚀性能也先升高而后降低。     

淬火介质对7055铝合金晶界析出行为的影响

采用透射电镜研究了淬火介质对7055铝合金晶界析出相及无沉淀析出带的影响。结果表明，空气淬火时，合金冷却过程在晶界上析出η平衡相。合金经室温水淬及沸水淬火合金时效后，晶界析出相尺寸差别小，呈链状连续分布；晶界无沉淀，析出带较窄，平均宽度分别约为33nm和43nm。空气淬火合金时效后晶界析出相尺寸差别较大，呈不连续分布；晶界无沉淀，析出带很宽，约102nm。对其原因进行了分析和讨论。     

一种基于DTW的新型故事时间序列相似性度量方法

现有时间序列相似性度量方法在进行股市序列相似性分析时,通常忽略成交量等其他重要因素对股价的影响,从而导致序列聚类、分类不精确。针对这一问题,本文提出了新的股市时间序列相似性度量方法。该方法在动态时间弯曲算法的基础上,通过引进时间衰竭因子,并结合成交量因素,给出了股市序列的最终度量公式。为了证明提出方法的可行性和有效性,本文实验部分通过选取家电等三个行业中的股票数据进行测试。实验结果表明,基于动态时间弯曲(Dynamic time warping,DTW)的新型股市时间序列相似性度量方法能够在保持股票序列形态特征的基础上,较好地解决股市技术分析中量价关系问题,从而更有效地应用于股市技术分析里关于模式发现等领域。