微量La_2O_3对钼的韧化作用  

Toughness of La_2O_3 -doped Mo alloy

作　　者：张久兴[1] 刘燕琴[1] 刘丹敏[1] 周美玲[1] 左铁镛[1] 

机构地区：[1]北京工业大学新型功能材料教育部重点实验室,北京100022

出　　处：《中国有色金属学报》2004年第1期13-17,共5页The Chinese Journal of Nonferrous Metals

基　　金：国家重点基础研究发展规划资助项目(G1998061316);北京市科技新星计划联合资助项目(952872200)

摘　　要：研究了添加La2O3后钼的韧性及其韧化机制。借助于拉伸、弯曲方法测定了Mo La2O3材料的断裂韧性KⅠC和韧脆转变温度(DBTT),并用SEM、TEM、AES等方法对Mo La2O3材料的变形、断裂特征和组织结构进行了分析。研究结果表明:烧结态Mo La2O3材料的KⅠC值达到24.76MPa·m1/2,是纯钼的2.5倍多,而且高于热锻空冷态TiC ZrC Mo钼合金。经1900℃退火的Mo La2O3板,其韧脆转变温度降低至-60℃,较同样状态的纯钼板降低了80℃,故La2O3对钼具有显著的韧化效果。AES结果表明,添加La2O3并不改变C、N、O等致脆杂质在钼晶界上的分布状态。Mo La2O3材料的韧化主要归因于其抗裂纹扩展能力的提高,而这与La2O3粒子改变钼中的位错分布及组态有关。并提出了一种新的韧化机制—硬脆第二相的韧化机制,能很好解释实验结果。The K_(ⅠC) and DBTT of both sintered and recrystallized Mo alloy doped with La_2O_3(Mo-La_2O_3) as well as unalloyed molybdenum were tested and the microstructure was investigated by SEM, TEM and AES. The results show that the K_(ⅠC) of Mo-La_2O_3 alloy reaches to 24.76MPa·m^(1/2), which is 2.5 times as much as that unalloyed Mo. The DBTT of Mo-La_2O_3 sheet annealed at 1900℃ for 60 min is decreased to -60℃, which is 80℃ lower than that of unalloyed Mo. The Mo-La_2O_3 alloy has similar equiaxed grain structure with the unalloyed Mo. The AES analysis revealed that the same content of interstitial impurities exist on grain boundaries of Mo-La_2O_3 and unalloyed Mo. A toughening mechanism was proposed to be that large number of dislocations were pinned around La_2O_3 particles, shorting the efficient slip length and decreasing the dislocations pile-up on grain boundaries of Mo. The toughness improvement of Mo-La_2O_3 alloy was attributed to the relax of stress concentration at grain boundaries of Mo-La_2O_3 alloy and the weaker tendency to intergranular fracture on grain boundaries.

关 键 词：钼 La203 断裂韧性 DBTT 第二相韧化 韧-脆转变温度 NET装置 

分 类 号：TL341[核科学技术—核技术及应用] TG146.412[一般工业技术—材料科学与工程]