共查询到20条相似文献，搜索用时 62 毫秒
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马云锐 《通化师范学院学报》2009,30(12):23-24
该文研究了采用机械合金化法制备Ni—Ti—Nb非晶态合金材料,用X射线衍射仪（XRD）、扫描电子显微镜（SEM）对经不同机械合金化时间得到的Ni—Ti—Nb混合粉末进行了分析,结果表明Ni—Ti—Nb混合粉末球磨10h后可实现机械合金化。随着球磨持续进行,Ni、Ti、Nb合金粉末之间相互扩散,当扩散速度增加到一定程度,来不及形成有序结构,而形成Ni—Ti—Nb系非晶合金． 相似文献
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通过机械合金化球磨反应制备了含不同组元数和等摩尔比组成的合金体系Mg-TiV-Cr-Ni,利用XRD、EDS能谱分析、TEM以及DSC/TG热分析了组元数及热处理对合金球磨产物微观组织和相形成规律的影响.结果表明:经20h球磨后,二元合金Mg-Cr、Mg-V与MgTi体系几乎不发生合金化反应,随合金主组元数的增加,高混合熵效应可促进多元合金组元之间的相互反应和固溶,其中五元高熵合金Mg Ti VCr Ni球磨产物可形成富Mg的非晶相与贫Mg的纳米晶BCC型相.经400~600℃热处理后,合金Mg Ti VCr Ni球磨组织中的非晶相经晶化后转变为新的和贫Mg的BCC型结构相,当温度提高至600℃时,残余的金属Cr逐渐在BCC型相中固溶,最终形成稳定的单相BCC型固溶体.球磨高熵合金Mg Ti VCr Ni中形成的BCC型固溶体结构具有较高的热稳定性. 相似文献
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《甘肃高师学报》2022,(2)
通过机械合金化球磨反应制备了含不同组元数和等摩尔比组成的合金体系Mg-TiV-Cr-Ni,利用XRD、EDS能谱分析、TEM以及DSC/TG热分析了组元数及热处理对合金球磨产物微观组织和相形成规律的影响.结果表明:经20h球磨后,二元合金Mg-Cr、Mg-V与MgTi体系几乎不发生合金化反应,随合金主组元数的增加,高混合熵效应可促进多元合金组元之间的相互反应和固溶,其中五元高熵合金Mg Ti VCr Ni球磨产物可形成富Mg的非晶相与贫Mg的纳米晶BCC型相.经400600℃热处理后,合金Mg Ti VCr Ni球磨组织中的非晶相经晶化后转变为新的和贫Mg的BCC型结构相,当温度提高至600℃时,残余的金属Cr逐渐在BCC型相中固溶,最终形成稳定的单相BCC型固溶体.球磨高熵合金Mg Ti VCr Ni中形成的BCC型固溶体结构具有较高的热稳定性. 相似文献
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采用机械合金化方法制备了Al82Fe5Zr5Ce8非晶态合金,用扫描电镜、X射线衍射、差热分析等方法分析了非晶态合金Al82Fe5Zr5Ce8的形貌、结构、热稳定性。结果表明：Al82Fe5Zr5Ce8混合粉末经过机械合金化球磨200h后达到了非晶状态。热分析表明非晶态Al82Fe5Zr5Ce8合金的晶化分两阶段进行,在723K和783K经8h的退火后,非晶态Al82Fe5Zr5Ce8合金达到了完全晶化状态,该状态下出现了很多种中间化合物相,经不同温度退火后晶化产物相基本相同。利用Kissinger方程分析了两个晶化过程的晶化激活能,对应过程的晶化激活能分别是475.6 k J/mol和408.8 k J/mol。 相似文献
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为了探讨机械合金化法制备Fe-Si合金的有效性,研究了Fe-Si的机械合金化及其相变.用扫描电子显微镜、X射线能谱仪和X射线衍射仪研究了Fe-si粉体的机械合金化过程,结果表明:球磨初期,韧性的Fe粉体磨成块状,脆性的Si粉体磨成小颗粒;随着球磨强度的增加,韧性的Fe粉体形成层片状而脆性的Si颗粒则分布在Fe的层片间或层片上;最后,Fe-Si粉体通过原子扩散实现机械合金化.因此,Fe,Si粉体在球磨机转速400 r/min、球料比40:1的条件下,球磨15 h可以合金化.机械合金化后的Fe-Si合金经过1 243 K退火1 h可得到单相的Ot-αFeSi2;机械合金化后的Fe-Si合金经过1 243 K退火1 h再冷却到1 073 K保温1 h可得到单相的β-FeSi2.因而,单相的α-FeSi2或β-FeSi2可通过对机械合金化的Fe-Si合金进行热处理获得. 相似文献
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ZnS∶Cu纳米微粒的制备及其光学性能 总被引：1，自引：0，他引：1
利用微乳液法制备出ZnS∶Cu纳米微粒 .透射电子显微镜 (TEM )和动态光散射 (DLS)测试结果表明 ,所得微粒粒径为 2～ 8nm .XRD结果表明 ,ZnS∶Cu纳米微粒为立方晶型结构 ,与体材料ZnS的晶型结构一致 ;在紫外吸收光谱中 ,ZnS∶Cu纳米微粒吸收峰蓝移 .发射光谱表明ZnS∶Cu纳米微粒产生一个位于 482nm的绿色发射带 相似文献
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在液相中依靠超声粉碎和剪切搅拌相结合的方法成功制备了Sn-Cd合金纳米微粒,并利用透射电子显微镜（TEM）、X-射线粉末衍射（XRD）、热分析（TG-DTA）等手段对合金纳米微粒的形貌和结构进行了表征,同时对合金纳米微粒用作润滑油添加剂的摩擦学性能进行了探讨. 相似文献
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利用浸渍法制备了Pd/Al2O3催化剂,采用X射线衍射(XRD)、透射电子显微镜(TEM)和X射线光电子能谱(XPS)研究了Pd在载体Al2O3中的分布状态和价态.结果表明纳米尺寸的Pd颗粒主要以单质形式高度分散在载体Al2O3上,部分呈氧化态. 相似文献
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《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help? 相似文献
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《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love. 相似文献
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Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject. 相似文献
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Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities. 相似文献
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RUZBEHANI Mohsen 《重庆大学学报(英文版)》2004,3(1):20-25
1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec… 相似文献
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唐芳 《读与写:教育教学刊》2008,5(6)
During interview with English majors, it was found that a majority of students expressed disappointment with their experience of English literature classes. Students' dislike of learning English literature appears to be the major problem of teaching English literature in China. Reader response approach is a good way to solve this problem. In this paper, I explain the rationale behind the reader response approach, such as its origin, definition, features, assumptions, and strategies. Then I illustrate how reader response approach works as a teaching strategy by presenting several teaching models. At last I evaluate its usefuiness for teachers and present the advantages of reader response approach in Chinese context. 相似文献