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【期刊论文】Role of yttrium in glass formation of Fe-based bulk metallic glasses
吕昭平, Z. P. Lu, C. T. Liu, W. D. Porter
APPLIED PHYSICS LETTERS VOLUME 83, NUMBER 13, 29 SEPTEMBER 2003,-0001,():
-1年11月30日
In this study, we discovered that a small addition of Y is very effective in improving glass-forming ability of Fe-based alloys. As-cast bulk amorphous alloys containing 2 at.% Y showed large thermal stability, with glass transition temperatures above 900 K and supercooled liquid regions above 55 K, and high strength, with Vickers hardnesses larger than HV 1200. The beneficial effect of Y on glass formation is twofold: (1)Y adjusted the compositions closer to the eutectic and thus lowered their liquidus temperatures, and (2) Y improved the manufacturability of these alloys by scavenging the oxygen impurity from it via the formation of innocuous yttrium oxides.
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吕昭平, H. Bei, , Z. P. Lu, E. P. George
PHYSICAL REVIEW LETTERS VOLUME 93, NUMBER 12, 17 SEPTEMBER 2004,-0001,():
-1年11月30日
The mechanical behavior of bulk metallic glasses (BMGs) was investigated by nanoindentation with a spherical indenter. The transition from perfectly elastic behavior to plastic deformation was clearly observed as a pop-in event (sudden displacement excursion) on the load-displacement curves. Hertzian stress analysis was used to describe fully the load-displacement behavior during elastic deformation and to determine the theoretical shear strengths of the BMGs.
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【期刊论文】A new glass-forming ability criterion for bulk metallic glasses
吕昭平, Z.P. Lu, C.T. Liu
Acta Materialia 50 (2002) 3501-3512,-0001,():
-1年11月30日
A new indicator of glass-forming ability (GFA) for bulk metallic glasses (BMGs) is proposed based on crystallization processes during cooling and reheating of the supercooled liquid. The interrelationship between this new parameter and the critical cooling rate or critical section thickness is elaborated and discussed in comparison with two other representatives, i.e. reduced glass transition temperature Trg ( =Tg /Tl, where Tg and Tl are the glass transition temperature and liquidus temperature, respectively) and supercooled liquid range △Txg ( =Tx-Tg, where Tx is the onset crystallization temperature and Tg the glass transition temperature). Our results have shown that △Txg alone cannot infer relative GFA for BMGs while the new parameter g, defined as Tx/ (Tg +Tl), has a much better interrelationship with GFA than Trg. An approximation of the critical cooling rate and critical section thickness for glass formation in bulk metallic glasses is also formulated and evaluated. 2002 Published by Elsevier Science Ltd on behalf of Acta Materialia Inc.
Casting, Metallic glasses, Differential thermal analysis, Glass-forming ability, Order–disorder phenomena
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吕昭平, Z.P. Lu, H. Tan, Y. Li, S.C. Ng
Scripta mater. 42 (2000) 667-673,-0001,():
-1年11月30日
Differential thermal analysis (, DTA), , Metallic glasses, Melt-spinning, Glass forming ability (, GFA),
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【期刊论文】Direct observation of a concealed glass transition in a Mg–Ni–Nd metallic glass
吕昭平, Z. P. Lu, C. T. Liu, C. H. Kam, Y. Li
APPLIED PHYSICS LETTERS VOLUME 82, NUMBER 6, 10 FEBRUARY 2003,-0001,():
-1年11月30日
Glass transition and crystallization behavior of Mg75Ni10Nd15 metallic glass has been studied by a temperature-modulated differential scanning calorimeter (TMDSC) and a normal differential scanning calorimeter (DSC). The truly vitreous state of the as-spun Mg75Ni10Nd15 alloy was confirmed by the direct observation of the glass transition through TMDSC measurements, which was not perceptible in the normal DSC heating scans. It was concluded that the glass transition signal was concealed by the relatively strong concurrent signal of the primary crystallization. This was further confirmed by the fact that the glass transition was revealed by both TMDSC and DSC for the samples with negligible heat release from the primary crystallization.
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