正电子湮没谱研究Nb在TiAl合金中的掺杂效应  

STUDY OF DOPING EFFECT OF Nb IN TiAl ALLOY BY POSITRON ANNIHILATION SPECTRUM

作　　者：张兰芝[1] 王宝义[1] 王丹妮[1] 魏龙[1] 林均品[2] 王文俊[2] 

机构地区：[1]中国科学院高能物理研究所核分析技术重点实验室 [2]北京科技大学新金属材料国家重点实验室,北京100083

出　　处：《金属学报》2007年第3期269-272,共4页Acta Metallurgica Sinica

基　　金：国家自然科学基金项目10275076和10475096资助~~

摘　　要：利用正电子湮没寿命谱(PALS)和符合Doppler展宽(CDB)技术研究了Ti_(51)Al_(49)合金中Nb的掺杂效应．结果表明:低含量掺杂时,Nb原子主要偏聚在合金晶界处,提高了晶界位置的自由电子密度,有利于改善合金的室温韧性;而较高含量的Nb掺杂时,由于形成了新的晶体结构,合金基体及晶界处的自由电子密度减少,导致合金的脆性增加．Positron annihilation lifetime and coincidence Doppler broadening measurements have been performed for Ti51Al49 alloy with different amounts of Nb. The experimental results indicate that when a low amount of Nb atoms is added into Ti51Al49 alloy, the Nb atoms mainly aggregate at grain boundaries, which increased the free electron density at boundaries and improved the toughness at room temperature of TiAl alloys. In contrast, the densities of free electron at grain boundaries and in bulk decreased for high Nb doped alloy, due to the formation of the new ordering structure, which increases the brittleness of TiAl alloys.

关 键 词：正电子湮没寿命 二维符合Doppler TIAL合金 

分 类 号：TG146.2[一般工业技术—材料科学与工程] O571.33[金属学及工艺—金属材料]