Investigation on Correlation between the Modified Criterion and the Glass-Forming Ability for Metallic Glasses

2010 ◽  
Vol 97-101 ◽  
pp. 591-596
Author(s):  
Wen Bin Sheng ◽  
Chun Ming Zhang ◽  
Wan Li Gu
Keyword(s):  
Aqueous Solutions ◽  
Cooling Rate ◽  
Metallic Glasses ◽  
Statistical Correlation ◽  
Glass Forming Ability ◽  
Correlation Parameter ◽  
Glass Forming ◽  
A Value ◽  
The Relationship ◽  
Modified Equation

A modified criterion γ’ (=Tx/(1.5Tg+Tl) of glass-forming ability (GFA) for metallic glasses is suggested on the basis of present criterion γ (=Tx/(Tg+Tl) that correlates well with some systems including metallic glasses, some glassy oxides and some cryo-protective aqueous solutions. Results show that the modified criterion γ’ shows stronger correlation with the critical cooling rate Rc for metallic glasses than the criterion γ, which is demonstrated by a value increase in the statistical correlation parameter R2 from 0.9022 to 0.9037. Furthermore, a modified equation is given to reflect the relationship between γ’ and Rc.

Critical Cooling Rate and Thermal Stability in Zr-Ti-Cu-Ni-Be Bulk Metallic Glasses

2000 ◽  
Vol 644 ◽  
Author(s):  
Theodore A. Waniuk ◽  
Jan Schroers ◽  
William L. Johnson
Keyword(s):  
Thermal Stability ◽  
Cooling Rate ◽  
Metallic Glasses ◽  
Glass Forming Ability ◽  
Liquid Region ◽  
Continuous Increase ◽  
Critical Cooling Rate ◽  
Glass Forming ◽  
The Relationship ◽  
Tie Line

AbstractThe crystallization behavior of a series of alloys in the Zr-Ti-Cu-Ni-Be system is studied. Upon cooling from the molten state with different rates, alloys with compositions ranging along a tie line from (Zr75Ti25)55(Ni45Cu55)22.5Be22.5 (Vit1) to (Zr85Ti15)55(Ni57Cu43)17.5Be27.5 (Vit4) show a continuous increase in the critical cooling rate to suppress crystallization. In contrast, thermal analysis of the same alloys shows that the undercooled liquid region, the temperature difference between the glass transition temperature and the crystallization temperature, is largest for compositions midway between the two endpoints, revealing that glass forming ability does not correlate with thermal stability. The relationship between the change in glass forming ability and thermal stability is discussed with reference to a chemical decomposition process.

Quantitative Evaluation of the Glass Forming Ability of (Cu-Zr) Based Glass Alloys with Thermodynamics Method

2011 ◽  
Vol 239-242 ◽  
pp. 1622-1625
Author(s):  
Hui Qiang Li ◽  
Long Fei Liu
Keyword(s):  
Cooling Rate ◽  
Nucleation Rate ◽  
Glass Forming Ability ◽  
Crystalline Fraction ◽  
Critical Cooling Rate ◽  
Glass Forming ◽  
Element Number ◽  
The Relationship ◽  
Peak Value ◽  
Crystalline Growth

Along nucleation → crystalline growth →crystalline fraction → critical cooling rate, the relationship between the nucleation, elements, cooling rate and the Glass Forming Ability of (Cu-Zr) based glass alloys is quantitatively studied with thermodynamics method, and a better method to evaluate the critical cooling rate of glass alloys is also proposed in this paper. The computed results show that: (1) with the increase of element number, the steady state nucleation rate drops gradually. From Cu-Zr, Cu-Zr-Al, Cu-Zr-Al-Ni, to Cu-Zr-Al-Ni-Ti, the peak value of nucleation rate decreases from 1021mol-1s-1to 1013mol-1s-1. It is also found the nucleation rate both drops with the substitution of Ni with Cu or Al with Zr; (2) with the increase of cooling rate, the nucleation rate drops sharply. When the cooling rate reaches 103K/s, the nucleation rates of Cu64Zr36, Cu54Zr42.5Al3.5, Cu55Zr40Al5and Cu30Zr55Al10Ni5drop to 109mol-1s-1, 106mol-1s-1, 107mol-1s-1and 103mol-1s-1accordingly.

Formation and Optimization of Cu-Based Cu-Zr-Al Bulk Metallic Glasses

2005 ◽  
Vol 475-479 ◽  
pp. 3381-3384 ◽  
Author(s):  
Qing Wang ◽  
Jian Bing Qiang ◽  
Ying Min Wang ◽  
Jun Hai Xia ◽  
Xin Fang Zhang ◽  
...  
Keyword(s):  
Metallic Glasses ◽  
Ternary Phase ◽  
Ternary Phase Diagram ◽  
Bulk Metallic Glasses ◽  
Glass Forming Ability ◽  
Glass Forming ◽  
The Third ◽  
A Value ◽  
Composition Optimization ◽  
Specific Cluster

The present paper covers in a comprehensive manner the formation of the Cu-based Cu-Zr-Al bulk metallic glasses (BMGs). Composition optimization for BMG formation is realized by using an “e/a-variant criterion”. This criterion is incorporated into the ternary phase diagram by a straight composition line, which is defined by linking a specific binary composition to the third element. There e/a-variant composition lines are constructed: (Cu9Zr4)1-xAl, (Cu61.8Zr38.2)1-xAlx and (Cu56Zr44)1-xAlx, where Cu9Zr4, Cu61.8Zr38.2 and Cu56Zr44 are specific cluster compositions in the Cu-rich Cu-Zr binary system. No Cu-based BMGs are obtained in the composition line (Cu9Zr4)1-xAlx using our suction casting techniques, while BMGs are obtained within an e/a span from 1.24 to 1.3 and from 1.28 to 1.36 respectively along the other two lines (Cu61.8Zr38.2)1-xAlx and (Cu56Zr44)1-xAlx. Thermal analysis results indicate that the BMGs on every composition line manifest increased thermal stability and glass forming ability (GFA) with increasing e/a ratios. The maximum appears in Cu58.1Zr35.9Al6 with the e/a value of 1.3, which belongs to the (Cu61.8Zr38.2)1-xAlx series. The characteristic thermal parameters of this BMG are Tg = 760K, Tg/Tm = 0.659 and Tg/Tl = 0.648, which are all superior to those reported for the known Cu55Zr40Al5 BMG.

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