原始Mg粉形状对Mg-B体系成相行为的影响  

INFLUENCE OF RAW Mg POWDER SHAPE ON BEHAVIOR OF PHASE FORMATION FOR Mg-B SYSTEM

作　　者：闫世成[1] 闫果[2] 卢亚锋[2] 刘春芳[2] 周廉[1] 

机构地区：[1]西北工业大学材料学院,西安710072 [2]西北有色金属研究院,西安710016

出　　处：《金属学报》2007年第4期358-362,共5页Acta Metallurgica Sinica

基　　金：国家自然科学基金项目50472099;国家重点基础研究发展计划项目2006CB601004;西北工业大学博士论文创新基金资助

摘　　要：采用球形Mg粉(Q-Mg)、屑状Mg粉(X-Mg)和无定形B粉,按照MgB_2的化学计量比充分混合后,在10 MPa的压力下压制成块材,分别在650,750和800℃下进行烧结．X射线衍射(XRD)结果表明,Q-Mg样品的成相速率远低于X-Mg样品、扫描电镜(SEM)观察照示,样品中的孔洞形状和尺寸依赖于初始Mg粉的形状和尺寸,差示扫描量热法(DSC)研究结果显示,两类样品在升温过程中,均先后发生了固-固反应、Mg熔化以及液-固反应．但是,由于球形粉末表面积较小,表面能较大,且表面原子活性较差,导致了Q-Mg样品的固-固反应起始温度比X-Mg样品高出53．7℃．基于DSC,XRD和SEM研究结果可知,球形Mg粉提高了固-固反应温度并延缓了低温下的Mg-B反应速率,但不改变MgB_2晶体的形成和生长机制．MgB2 bulks were prepared by using the spherical magnesium powder （Q-Mg） and scrapping magnesium powder （X-Mg） as raw materials. The two kinds of magnesium powder were mixed respectively with amorphous boron powder with a nominal stoichiometry of MgB2, then pressed into pellets under a pressure of 10 MPa. The pellets were sintered at 650, 750 and 800 ℃, respectively. XRD results for the sintered samples show that the phase formation rate of Q-Mg series samples is lower than that of X-Mg series samples. SEM observations show that the shape and size of holes are evidently correlated with the shape and size of the raw magnesium powder. DSC results indicate that the solid-solid reaction , Mg melting and liqiud-solid reaction during increasing temperature occur in turn for the X-Mg and Q-Mg series samples. However, because of the small surface area, large surface energy and low activity of the surface atom the starting temperqture of the solid-solid reaction of Q-Mg sample is 53.7℃ higher than that of X-Mg sample. The results of DSC, XRD and SEM also showed that the starting temperqture of the solid-solid reaction increases, the reaction rate between Mg and B decreases at low temperature if the spherical magnesium powder was used as raw materials, but the formation and growth mechanism of MgB2 crystals are not changed. KEY WORDS MgB2, powder shape, sintering

关 键 词：MGB2 粉末形状 烧结 

分 类 号：TG132.26[一般工业技术—材料科学与工程]