摘要
研究了液态Zr_(35)Al_(23)Ni_(22)Gd_(20)合金在深过冷快速凝固条件下的亚稳相分离和双非晶相形成机理.实验发现,在平衡条件下其凝固组织由3种晶体相构成,诱发亚稳相分离的临界过冷度约为516 K(0.37TL).当过冷度达到624 K(0.45TL)时,分离后的富Zr液相发生非晶转变,形成非晶AM-Zr相;当过冷度进一步增大到714 K(0.52TL)时,富Gd液相发生非晶转变形成非晶AM-Gd相.同时,过冷度和冷却速率的增大导致亚稳相分离机制由形核长大型转变为调幅分解型,双非晶相的组织形貌由球状向网状转变.双相非晶合金的平均硬度和杨氏模量由自由体积、相体积分数和双非晶相结构共同支配,呈现出先减小后增大的变化规律.双非晶相的形成有利于合金应力加载过程中的能量耗散,促进了多重剪切带的产生,提高了非晶合金的塑性.
Duplex metallic glass with two amorphous phases has been extensively investigated for desirable strength and plasticity.In this paper,the metastable phase separation and dual amorphous phase formation of liquid Zr_(35)Al_(23)Ni_(22)Gd_(20)alloy under substantial undercooling condition and rapid cooling condition are studied by drop tube technology.The equilibrium solidification structure consists of three crystalline phases,while the critical undercooling temperature of metastable phase separation is determined to be 516 K(0.37TL).The separated Zrrich liquid phase undergoes amorphous transition and becomes amorphous AM-Zr phase with the composition of Zr45Ni23Al23Gd9 when alloy undercooling is increased to 624 K(0.45TL).After that,the Gd-rich liquid phase forms amorphous AM-Gd phase with the composition of Gd_(39)Al_(22)Ni_(20)Zr_(19)at larger undercooling of 714 K(0.52TL).With the increase of liquid undercooling and cooling rate,the kinetic mechanism of metastable phase separation changes from nucleation and growth type to spinodal decomposition type,and consequently the microstructure of dual amorphous phases transforms from a spherical morphology to a reticular structure.The average hardness and Young’s modulus,which are influenced by free volume,phase volume fraction and structure of dual amorphous phases,exhibit a complex variation of first increasing and then decreasing with the decrease of alloy droplet size.The formation of dual amorphous phases is in favor of the energy dissipation and the generation of multiple shear bands during mechanical compression,which improves the plasticity for this kind of amorphous alloy.
作者
武博文
胡亮
耿德路
魏炳波
Wu Bo-Wen;Hu Liang;Geng De-Lu;Wei Bing-Bo(School of Physical Science and Technology,Northwestern Polytechnical University,Xi’an 710072,China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2023年第21期287-296,共10页
Acta Physica Sinica
基金
国家重点研发计划(批准号:2021YFA0716301)
国家自然科学基金(批准号:52088101,52171047)资助的课题.
关键词
深过冷
快速凝固
亚稳相分离
双相非晶
liquid undercooling
rapid solidification
metastable phase separation
duplex amorphous alloy
