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采用Gleeble-1500D热模拟机高温等温压缩试验,研究了新型反应堆中子吸收材料-碳化硼-铝硅复合材料在应变速率为0.1~10s-1、变形温度为300~500℃条件下的流变应力特征.结果表明:该材料在试验条件下压缩变形时均存在稳态流变特征,应变速率和变形温度强烈影响试验材料流变应力;该流变应力随应变速率的提高而增大,随变形温度的升高而降低;采用Zener-Hollomon参数的双曲正弦函数描述该复合材料高温变形的峰值流变应力,获得峰值流变应力解析式,其热变形激活能为236.248 kJ/mol. 相似文献
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在Gleeble-1500热模拟实验机上对原位生成TiC颗粒增强钛基复合材料进行热压缩实验,研究变形温度为700~950 ℃、温度间隔为50 ℃,应变速率为10-3~1 s-1条件下的热变形行为,采用XRD、DSC、SEM、OM等实验手段对复合材料的相变点及变形后的显微组织等进行分析和测定.结果表明:流变应力随变形温度的升高和应变速率的降低而减小;在高应变速率条件下,绝热温升对流变应力的影响较为明显;动态再结晶是TiC钛基复合材料热变形的重要机制,变形温度越高,再结晶越易进行,变形速率越高,应变量越大,再结晶晶粒越细小. 相似文献
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在变形温度为300~450 oC、应变速率为0.01~1 s-1的条件下进行热压缩试验,对Mg-5Y-0.5Ce-0.5Zr镁合金的热变形行为进行了研究。结果表明,在热压缩变形过程中,该合金的流变应力随着变形温度和应变速率的变化而变化。在同一应变速率下,流变应力随着变形温度的增高而降低;在同一变形温度下,流变应力随着应变速率的减小而减小。该合金热压缩流变应力的本构方程可采用双曲正弦形式构建,热变形激活能Q为253 kJ/mol。 相似文献
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原位合成TiB2/6351复合材料的高温压缩流变行为 总被引:1,自引:0,他引:1
在Gleeble-1500D热模拟机上采用等温压缩实验,研究原位合成TiB2/6351复合材料在变形温度为300~ 550 ℃和应变速率为10-3~10 /s条件下的流变变形行为.结果表明:在实验范围内,该复合材料高温压缩时均存在稳态流变特征且属于正应变速率敏感材料;在低应变速率和较高温度条件下, 随变形程度的增加,流变应力增加到峰值后缓慢下降,逐渐趋于平稳,呈现明显的动态再结晶特征;而在较高应变速率和较低温度下,呈现明显动态回复特征;可用包含Arrhenius项的Zener-Hollomon参数描述TiB2/6351复合材料高温压缩流变行为.通过线性回归分析和优化计算,得出流变应力σ解析表达式中A、α和n分别为3.52×1010 /s、0.023 Mpa-1和7.33,其热变形激活能Q为170.10 kJ/mol. 相似文献
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在Gleeble-1500D热模拟实验机上对30ZrCp/W复合材料进行高温压缩实验,变形温度和应变速率分别为800℃~1 200℃和10-3 s^-1~1 s^-1,研究其高温压缩变形的流变应力行为.研究表明:随变形温度升高,复合材料的流变应力下降,在10-3s^-1和1200℃下,抗压强度为948.7 MPa.在800℃下发生伪塑性变形,未达到预设变形量,真应力-真应变曲线上表现出的塑性为伪塑性,其是由微裂纹的萌生-钝化引起的.随变形温度升高,复合材料发生动态回复再结晶.随应变速率升高,真应力-真应变曲线形状从“锯齿”型向“平滑”型转变.复合材料对应变速率不敏感,随应变速率升高,复合材料的流变应力略有升高.在800℃和1s^-1下,复合材料的抗压强度为1176.9MPa.用Arrhenius方程描述复合材料在1000℃~1200℃的热变形行为,变形激活能为811.4 kJ/mol. 相似文献
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在变形温度700~860 ℃、应变速率0.001~1 s-1下,对TB6合金进行热压缩变形,以研究TB6合金的热压缩流变应力行为.研究温度、变形量、应变速率等因素对TB6热变形流变应力的影响,建立了TB6合金热变形流变应力的本构模型方程.结果表明:合金在热压缩过程中,流变应力随着应变的增大而增加,达到峰值应力后逐渐趋于平稳;应力峰值随着应变速率的增大而增大,随着温度的升高而呈减小趋势. 相似文献
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M. Balaceanu V. Braic A. Kiss A. Vladescu C. Vasilescu O. Muresanu 《Surface & coatings technology》2008,202(11):2384-2388
Results on the deposition and characterization of TiOxNy/ZrOxNy multilayers, with bilayer periods of 20 and 400 nm, are presented. The coatings were deposited on TiNiNb alloy substrates by the pulsed magnetron sputtering method. The elemental composition, hardness, adhesion and corrosion resistance of the coatings were analyzed.As resulted from the XPS analysis, the individual layers consisted of a mixture of titanium or zirconium oxynitrides and corresponding oxides. X-ray analysis revealed that the coatings were amorphous. Only slight differences between the microhardness and adhesion values of the coatings with small and large bilayer period Λ were found. The experiments also showed that the multilayered coatings improved the corrosion resistance of the uncoated alloy and reduced the amount of ion release in artificial body fluids. 相似文献
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镍钛形状记忆合金(NiTi-SMA)具有较好的耐腐蚀和机械性能,在口腔和临床医学中有着大量而广泛的应用。NiTi-SMA腐蚀后释放Ni2+会引发细胞毒性和过敏反应,进一步提高NiTi-SMA的耐蚀性是目前生物医学材料领域发展的核心之一。本文对近年来国内外有关口腔医学和临床医学中常用NiTi-SMA的腐蚀研究现状进行了总结,同时也对NiTi-SMA增材制造及表面改性技术进行了评述,以期为开发高性能抗腐蚀生物医用NiTi-SMA提供一定的指导意义。 相似文献
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近年来,在高熵合金基础上发展起来的高熵陶瓷逐渐引起了研究者的广泛关注,其出现为开发高性能的无机非金属材料提供了新的设计思路。本文采用固相法制备了BaMO3基钙钛矿型高熵陶瓷Ba(Ti1/7Sn1/7Zr1/7Hf1/7Nb1/7Ga1/7Li(1/7-x))O3 (x = 0, 2.3%, 5.3%, 8.3%, 11.3%),并研究了Li含量对高熵陶瓷物相结构、微观形貌及介电性能的影响。结果表明,Li含量对陶瓷结构的影响不大,陶瓷均保持立方钙钛矿结构,且无杂相产生;陶瓷的晶粒尺寸相对较均匀。当x = 0时,即B位七元等摩尔比Ba(Ti1/7Sn1/7Zr1/7Hf1/7Nb1/7Ga1/7Li1/7)O3高熵陶瓷,其介电常数达到了最大值2920 (@100 Hz),相较于已报道的不掺Li的六元高熵钙钛矿陶瓷Ba(Ti1/6Sn1/6Zr1/6Hf1/6Nb1/6Ga1/6)O3提升了近50倍。 相似文献
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Qi Wang Xiaomin RenLijuan Zhang Yue YangTianhe Li Hui HuangYongqing Huang Shiwei Cai 《Journal of Alloys and Compounds》2011,509(18):5631-5636
Zinc-blende BxAl1−xAs and BxAl1−x−yInyAs alloys have been grown on exactly oriented (0 0 1)GaAs substrates by low pressure metalorganic chemical vapor deposition (LP-MOCVD). The influence of susceptor coating, growth temperature and gas-phase boron mole fraction on boron incorporation into AlAs has been comprehensively investigated. It has been found that boron incorporation into AlAs could be enhanced and the optimal growth temperature range of BxAl1−xAs alloys changed from 580 °C to 610 °C when SiC-coated graphite susceptors were replaced by the non-coated ones. In this study, the maximum boron composition x of 2.8% was achieved for the pseudomorphically strained BxAl1−xAs alloys. AFM measurements show that RMS roughness of BxAl1−xAs alloys increased sharply with the increase of gas-phase boron mole fraction. Raman spectra of BxAl1−xAs alloys show a linear increase of the BAs shift with boron composition x. Based on BAlAs deposition, bulk BxAl1−x−yInyAs (x = 1.9%) quaternary alloy was grown lattice-matched to GaAs successfully. Moreover, 10-period BAlAs/GaAs and BAlInAs/GaAs MQW heterostructures were also demonstrated. 相似文献
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本文运用溶胶-凝胶燃烧法合成了双钙钛矿型LaNixCo1-xO3(LNCO)纳米材料,利用粉末冶金和热挤压技术制备了相应的Ag/LNCO触点材料及元件样品。重点考察了不同Ni、Co含量对Ag/LNCO触点材料微观结构、物相组成、物理性能、力学性能及电寿命服役能力的影响,对其电弧侵蚀失效行为进行了研究,并与SnO2粉体增强Ag基触点材料进行对比。结果表明:溶胶凝胶法合成的LNCO纳米颗粒粒径为20-30 nm,经粉末冶金工艺制备的Ag/LaNi0.5Co0.5O3触点材料电学性能和电寿命都优于Ag/SnO2触点材料,其电阻率低至2.10 μΩ?cm,电寿命性能达到51287次。表明Ag/LaNi0.5Co0.5O3触点材料性能较佳,是一种可以取代Ag/CdO的新型触点材料。 相似文献
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Ganghua ZhangGuobao Li Fuqiang HuangFuhui Liao Kuo LiYinxia Wang Jianhua Lin 《Journal of Alloys and Compounds》2011,509(41):9804-9808
Superconductors Ba1−xKxBiO3 and body-centered double perovskites Ba1−xKxBi1−yNayO3 have been selectively synthesized by a facile hydrothermal route. The appropriate ratio and adding sequence of initial reagents, alkalinity, reaction temperature and time are the critical factors that influence the crystal growth of the compounds. The purity and homogeneity of the crystals were detected by the ICP, SEM, EDX and TEM studies. Magnetic measurements show that the superconducting transition temperatures TC of Ba1−xKxBiO3 decrease from 22 K (for x = 0.35) to 8 K (for x = 0.55) with increasing the K doping level. 相似文献
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The a.c. susceptibility and high field magnetization on TbRh2−xPdxPdxSi2 and TbRu2−xPdxSi2 compounds were investigated up to 140 kOe. The (T,x) magnetic phase diagrams were determined. For both systems, an increase in the Pd content causes a decrease in the Néel temperature and changes the magnetization curves. 相似文献
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Hailong ZhaoDongming Yao Feng QiuYumei Xia Qichuan Jiang 《Journal of Alloys and Compounds》2011,509(5):L43
A modified Al-Cu alloy with high tensile strength and ductility of about 574.0 MPa and 10.4%, respectively, was obtained by adding multiple rare earth oxides (PrxOy and LaxOy) as modifier. Compared with the unmodified Al-Cu alloy, the tensile strength and ductility of the modified sample were increased by 24.3% and 42.5%, respectively. The improvement both in the strength and ductility may attribute to the finer crystal grains and dendrites, more homogeneously distributed θ′ phase precipitates and the intermetallic compounds formed at the crystal grain boundaries as well as in the space of the dendrites. 相似文献
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采用Ti/Cu/Ni中间层对Si3N4陶瓷进行二次部分瞬间液相(PTLP)连接,研究连接工艺参数对Si3N4/Ti/Cu/Ni连接强度的影响,同时研究了连接强度随试验温度的变化规律。结果表明,在该试验条件下,室温连接强度随着二次连接温度的提高和二次保温时间的延长而提高,改变连接工艺参数对Si3N4/Ti/Cu/Ni二次PTLP连接界面反应层厚度无明显影响;连接强度在试验温度400℃时达到最大,随后随试验温度升高,连接强度降低,但在800℃前,其高温强度具有很好的稳定性。 相似文献