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研究生毕业前必须向学位委员会提交能够代表自己科研水平的学术论文,才能申请硕士、博士学位。学位论文就像一把尺子,标明了研究生的综合水平。因此,学位论文质量是学位授予工作的关键。研究生课程学习的成绩、知识的积累、研究的才干将集中展现于学位论文之中。 相似文献
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将冷轧法制备的Cu/Al复合材料在475-525℃温度下退火1-8min,采用有限元软件模拟了Cu/Al复合材料在退火过程中的温度场,并采用扫描电镜(SEM)、X射线衍射仪(XRD)、能谱仪(EDS)、电子背散射衍射(ESBD)、显微硬度计等研究了Cu/Al复合材料的显微组织与力学性能。结果表明:在Cu/Al复合材料界面依次生成了CuAl<sub>2</sub>、Cu<sub>9</sub>Al<sub>4</sub>和CuAl等3种金属间化合物,在Cu/Al界面层厚度小于4μm的退火工艺范围内,Cu和Al基体发生完全再结晶形成等轴晶,Cu、Al基体的显微硬度能够迅速的降低至低温长时间(350℃、1h)退火的硬度。另外,提出了金属间化合物初生相的形核机理,分析计算了高温短时退火工艺下的形核动力学,并提出了非等温条件下的金属间化合物生长厚度的经验数值方法。 相似文献
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To provide theoretical basis and practical guidance for preparing composite rods of external diameter no larger than 12 mm
by directly continuous casting, low melting point materials of lead and tin were selected to prepare composite rods of external
diameter 12 mm and inner diameter 8 mm with air pressing core filled continuous casting process. The orthogonal tests consisting
of three factors and three levels were designed to investigate the parameters of melting lead temperature, continuous casting
speed and air pressure that affect the performance of the composite rods. The results show that melting lead temperature is
the most important factor that influences the solid/liquid interface location; continuous casting speed is the most important
factor that influences the surface quality and lead and tin inter-diffusion amount; air pressure can improve the surface quality
obviously and make the rods easily drawn out, but the surface quality cannot get obvious improvement when the air pressure
is above 0.03 MPa. The composite rods have excellent surface quality, obvious intermediate layer, even thick clad, and metallurgical
bonding interface under the condition of melting lead temperature of 375 °C, continuous casting speed of 10 mm/min, and air
pressure of 0.03 MPa. 相似文献
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为改善430铁素体不锈钢的性能,主要研究了化学成分、铸坯等轴晶比例、热轧工艺制度、热卷退火工艺对材料组织和性能的影响.通过添加微量铝元素,同时降低过热度浇注,优化电磁搅拌工艺改善铸坯的结构.实验结果表明,通过不同热处理对比试验确定了最佳热处理工艺,热卷退火温度为950~1 000℃,保证了成品材料具有优异的力学性能和工艺性能. 相似文献
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Continuous unidirectional solidification of QAl9-4 Cu-Al alloy 总被引:3,自引:2,他引:1
Chang Guowei 《中国有色金属学会会刊》1999,9(3):8
1 INTRODUCTIONThecontinuousunidirectionalsolidificationtechnology,whichisestablishedbycombiningtheunidirectionalsolidificationwithcontinuouscasting,providesanewapproachforthestudyofsolidificationtheoryandthedevelopmentofnewmaterials.Itsemergencealsom… 相似文献
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