预热速率和Mg粒度对MgCNi_3致密度及相成份的影响  

EFFECT OF THE PREHEATING RATE AND SIZE OF MG POWDER ON THE RELATIVE DENSITY AND PHASE COMPOSITIONS OF MGCNI_3

作　　者：冯旺军[1,2] 何祖明[2] 夏咏梅[2] 张爽[2] 郭永庆[2] 杨华[1,2] 

机构地区：[1]甘肃省有色金属新材料省部共建国家重点实验室,甘肃兰州730050 [2]兰州理工大学理学院,甘肃兰州730050

出　　处：《低温物理学报》2010年第3期181-185,共5页Low Temperature Physical Letters

基　　金：甘肃省自然科学基金(项目编号:2007GS05336);甘肃省教育厅项目(项目编号:0803-03)资助的课题~~

摘　　要：用自蔓延高温合成法(SHS)制备了MgCNi_3超导块材,用XRD和SEM对试样进行了表征,理论计算和实验结果表明,如果预热温度太低,自蔓延过程不能进行,当预热温度大于620℃时才能用电弧引燃反应,预热速率越小试样越致密;Mg粒度越小反应后绝热温度越高,成相速率越快,并导致合成产物出现烧结现象,样品所形成的致密度和孔洞尺寸依赖于原始Mg粉的粒度,Mg粒度越小,试样越致密,孔洞越小,但是Mg粒度不同不改变晶粒的形成和生长机理.Superconductor bulk MgCNi_3 were synthesized by the Self-propagating High-temperature Synthesis （SHS） method.Theoretical calculations and experimental results showed that if the preheating temperature is too low,the sample could not be ignited by electrical arc.MgCNi_3 can be synthesized by SHS at over 620℃of preheat temperature.SEM observations indicated that the smaller the preheating rate is,the more dense the combustion-synthesized product is.In addition,the effect of Mg particle size in the Self-propagating High-temperature Synthesis on the products was studied by means of XRD and SEM.The results of XRD and SEM showed that the small particle size of Mg powder would induce a higher reaction temperature of the reaction,resulting in over sintering of the products.The relative density and size of holes are correlated with the size of the raw Mg powder.The smaller size of Mg powder,the denser relative density and the smaller size of holes,but the formation and growth mechanism of MgCNi_3 crystals are not changed by the size of the raw Mg powder.

关 键 词：SHS法 MgCNi_3超导块材 预热温度 预热速率 Mg粒度 

分 类 号：TM262[一般工业技术—材料科学与工程]