摘要
采用XRD、SEM和XRD对Nb-35Ti-4C合金热处理前后的相组成、界面结构、组织演变及力学行为进行研究。结果表明:热处理前后合金均由Nbss和(Nb,Ti)C构成。热处理过程中Nbss内部析出长条状的二次(Nb,Ti)C;(Nb,Ti)C内则析出长条状的二次Nbss。二次Nbss依附于fcc(Nb,Ti)C的密排面(111)面形核,与母相(Nb,Ti)C满足(N-W)位相关系:[011]_((Nb,Ti)C)//[001]_(Nbss), (111)_((Nb,Ti)C)//(110)_(Nbss)。碳化物与Nbss具有洁净良好的界面结合。热处理后单相(Nb,Ti)C变为(Nb,Ti)C+二次Nbss的共析组织。纳米压痕测试表明共析组织转变降低了碳化物的脆性,提高了合金的韧性。
The phase composition, interface structure, microstructure evolution and mechanical behavior of the Nb-35Ti-4C alloy before and after heat-treatment were comprehensively investigated using X-ray diffraction（XRD）, scanning electron microscopy（SEM）, transmission electron microscope（TEM） and Nano Indenter ＇XP. The results show that as cast and heat treated Nb-35Ti-4C alloy consists of Niobium solid solution（Nbss） and carbide of（Nb, Ti）C. The numerous secondary（Nb, Ti）C with several nanometers in size precipitates from Nbss matrix during heat treatment. Furthermore, the secondary Nbss with a reticular struct ure distribution also precipitates from carbide, the phase transformation of the carbide can be summarized as（Nb, Ti）C→（Nb, Ti）C＋Nbss. The secondary Nbss nucleates along the close-packed surface（111） of fcc（Nb, Ti）C at the early state of heat-treatment, and the strip secondary Nbss and the（Nb, Ti）C matrix adopt a well-defined orientation relationship（OR）： [0 11]（ Nb,Ti）C//[001]Nbss,（111）（Nb,Ti）C//（110）Nbss. The hard carbide has a strong bonding with the Nbss, and the eutectoid transformation of the large sized carbide after heat treatment leads to less possibility for the cracks formation on the carbide surface, which in turn improves the toughness.
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2017年第3期777-782,共6页
Rare Metal Materials and Engineering
基金
国家自然科学基金(51004077)
山东省科技发展计划(攻关)项目(2011GGX10226)
山东省优秀中青年科学家奖励基金(BS2010CL046)
