Correlation between supercooled liquid region and crystallization behavior with alloy composition of La-Al-Cu metallic glasses  

作　　者：ZHANG QingChao PANG ShuJie LI Yi ZHANG Tao 

机构地区：[1]Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100191, China [2]Department of Materials Science and Engineering, National University of Singapore, Singapore 117576, Singapore

出　　处：《Science China(Physics,Mechanics & Astronomy)》2011年第9期1608-1611,共4页中国科学：物理学、力学、天文学（英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant Nos. 50631010, 50771005 and 50771006);the National Basic Research Program of China (Grant No. 2007CB613900)

摘　　要：Bulk metallic glasses (BMGs) with large supercooled liquid region are promising materials for superplastic forming. In this paper, we demonstrate a microstructure-based strategy to pinpoint the composition with the largest supercooled liquid region in La 86 x Al 14 Cu x (x=16 at%-20 at%) metallic glass system. By monitoring the changes in crystallization behavior of the glassy alloys with composition to search for the alloys exhibiting eutectic crystallization, the glassy alloys with the largest supercooled liquid region in the given alloy system can be found. The metallic glasses with Cu contents of 16 at%-19 at% exhibited two crystallization peaks, and the primary crystallization product was identified to be α-La by means of DSC, XRD and TEM. The increase in Cu content resulted in the decay of the primary crystallization peak and the increase in onset temperature of crystallization, leading to the enlargement of supercooled liquid region. By further suppressing the α-La primary crystallization with increasing Cu content up to 20 at%, the eutectic crystallization of α-La and LaCu 13 through one crystallization reaction occurred upon heating, where the largest supercooled liquid region of 65 K for La 66 Al 14 Cu 20 glassy alloy was located. This study indicats that, in a given glassy alloy system, a larger supercooled liquid region can be achieved by optimizing the alloy compositions to suppress the primary crystallization.Bulk metallic glasses （BMGs） with large supercooled liquid region are promising materials for superplastic forming. In this paper, we demonstrate a microstructure-based strategy to pinpoint the composition with the largest supercooled liquid region in La86-xAl14Cux （x=16 at%-20 at%） metallic glass system. By monitoring the changes in crystallization behavior of the glassy alloys with composition to search for the alloys exhibiting eutectic crystallization, the glassy alloys with the largest supercooled liquid region in the given alloy system can be found. The metallic glasses with Cu contents of 16 at%-19 at% exhibited two crystallization peaks, and the primary crystallization product was identified to be α-La by means of DSC, XRD and TEM. The increase in Cu content resulted in the decay of the primary crystallization peak and the increase in onset temperature of crystallization, leading to the enlargement of supercooled liquid region. By further suppressing the α-La primary crystallization with increasing Cu content up to 20 at%, the eutectic crystallization of α-La and LaCu13 through one crystallization reaction occurred upon heating, where the largest supercooled liquid region of 65 K for La66Al14Cu20 glassy alloy was located. This study indicats that, in a given glassy alloy system, a larger supercooled liquid region can be achieved by optimizing the alloy compositions to suppress the primary crystallization.

关 键 词：bulk metallic glass supercooled liquid region CRYSTALLIZATION 

分 类 号：TG139.8[一般工业技术—材料科学与工程] TQ325.14[金属学及工艺—合金]