Critical Cooling Rate for the Glass Formation of Fe80-XCoxP13C7 Alloy

2013 ◽  
Vol 745-746 ◽  
pp. 799-808
Author(s):  
Kai Xu ◽  
Yan Wang ◽  
Qiang Li
Keyword(s):  
Amorphous Alloy ◽  
Cooling Rate ◽  
Thermodynamic Data ◽  
Glass Formation ◽  
Amorphous Alloys ◽  
Experimental Results ◽  
Bulk Amorphous Alloy ◽  
Cooling Rates ◽  
Critical Cooling Rate ◽  
Dta Curves

In this work, the critical cooling rate Rc for glass formation of a series of Fe80-xCoxP13C7 (x = 0, 5, 10, 15, 20 at.%) alloys was determined by means of constructing CCT curves using Uhlmanns method. The calculated critical cooling rates for x = 0, 5, 10, 15, 20 at.% are 621, 441, 548, 894, 922 K/s, respectively. These results well coincide with the maximum diameters of Fe80-xCoxP13C7 amorphous alloys determined by experiments varying with the content of Co. The calculated Rc was also on the reasonable order of magnitudes. In addition, the values of three common GFA criterions of Trg, ΔTx and γ were calculated according to the thermodynamic data determined from DSC and DTA curves of Fe80-xCoxP13C7 (x = 0, 5, 10, 15, 20 at.%) bulk amorphous alloy. The validity of these GFA criterions in the series of Fe80-xCoxP13C7 (x = 0, 5, 10, 15, 20 at.%) alloys were investigated and it was pointed out that these three GFA criterions were not able to explain the experimental results of the maximum diameters of Fe80-xCoxP13C7 amorphous alloys varying with the content x of Co.

Effects of RE on Critical Cooling Rate of Bearing-B Steel

2012 ◽  
Vol 535-537 ◽  
pp. 761-763 ◽  
Author(s):  
Yi Sheng Zhao ◽  
Xin Ming Zhang ◽  
Zhi Guo Gao
Keyword(s):  
Phase Change ◽  
Cooling Rate ◽  
Experimental Results ◽  
Cooling Rates ◽  
Critical Cooling Rate ◽  
The Law

The law of phase change of bearing-B steel during continual cooling was studied by adopting dilatometer. The CCT curves of bearing-B steel were drawn, and the effects of RE on critical cooling rates were studied. The experimental results show that the start temperatures of martensite TM was decreased from 438 to 404°C. The critical cooling rate was simultaneously decreased from 33 to 15°C/s.

Critical Cooling Rate of Y36Nd20Al24Co20 Bulk Amorphous Alloy

2014 ◽  
Vol 670-671 ◽  
pp. 86-89
Author(s):  
Shi Wen He
Keyword(s):  
Glass Transition ◽  
Amorphous Alloy ◽  
Cooling Rate ◽  
Supercooled Liquid ◽  
Supercooled Liquid Region ◽  
Glass Forming Ability ◽  
Bulk Amorphous Alloy ◽  
Liquid Region ◽  
Critical Cooling Rate ◽  
Glass Forming

A new bulk amorphous alloy, Y36Nd20Al24Co20, with a diameter of 5 mm was successfully fabricated by the method of equiatomic substitution for the Y element in Y56Al24Co20amorphous alloy. The values of the supercooled liquid region ∆Tx(=Tx-Tg), the reduced glass transition temperature Trg(=Tg/Tl) and the parameter γ (=Tx/(Tg+Tl)) for Y36Nd20Al24Co20bulk amorphous alloy are 60K, 0.605 and 0.415, respectively. The critical cooling rate of the Y36Nd20Al24Co20bulk amorphous alloy was determined to be 40 K/s, providing an indication that this alloy has a high glass-forming ability.

Method for Estimating the Critical Cooling Rate for Glass Formation from Isothermal TTT Data

2007 ◽  
Vol 336-338 ◽  
pp. 1874-1877 ◽  
Author(s):  
Dong Mei Zhu ◽  
Wan Cheng Zhou ◽  
Chandra S. Ray ◽  
Delbert E. Day
Keyword(s):  
Cooling Rate ◽  
Glass Formation ◽  
Lithium Disilicate ◽  
Nucleating Agent ◽  
Cooling Rates ◽  
Continuous Cooling Transformation ◽  
Critical Cooling Rate ◽  
Continuous Cooling ◽  
Transformation Curve ◽  
Continuous Cooling Transformation Curve

A method is proposed for estimating the critical cooling rate for glass formation and continuous cooling transformation curve (CCT) from isothermal TTT data. The critical cooling rates and CCT curves for a group of lithium disilicate glasses containing different amount of Pt as nucleating agent estimated through this method are compared with the experimentally measured values and it shows this method can give a reasonable estimation.

scholarly journals Application of 3D Balanced Growth Theory to the Formation of Bulk Amorphous Alloys

2021 ◽  
Vol 8 ◽  
Author(s):  
YaQi Wu ◽  
Yong Zhang ◽  
Tao Zhang
Keyword(s):  
Amorphous Alloy ◽  
Cooling Rate ◽  
Amorphous Alloys ◽  
Three Dimensional ◽  
Thin Strip ◽  
Growth Theory ◽  
Bulk Amorphous Alloy ◽  
Balanced Growth ◽  
Bulk Amorphous Alloys ◽  
Size Limitation

Since the emergence of amorphous alloys as a new class of materials, efficiency improvements have been made in optimizing the fabrication process, the mechanization of alloy formation, and the size of the alloys themselves. Amorphous alloys have been used in precision instruments as they possess excellent magnetic properties, corrosion resistance, wear resistance, high strength, hardness, toughness, high electrical resistivity, and electromechanical coupling properties. Because their hysteresis losses are lower than those of traditional transformer cores, the conversion efficiency of equipment has been significantly improved, thereby saving energy and protecting the environment. Hence, amorphous iron cores have replaced traditional materials. Amorphous alloys also show excellent performance as anti-corrosion and wear-resistant coatings. The process of preparing amorphous alloys starts with an amorphous alloy film obtained by evaporation deposition and then proceeds to the use of a high cooling rate ribbon spinning method to finally obtain a thin strip of an amorphous alloy. A widely used method of copper mold suction casting is then used to prepare the bulk amorphous alloy. The sizes of amorphous alloys have been continually increasing, which has resulted in increasingly serious challenges, such as cooling rate and thermal stability limitations. In addition, crystals can form at low cooling rates. The latent heat of crystallization is released when crystals are formed, which causes damage to the amorphous area so that the size of amorphous alloys is reduced. Because of these difficulties, new processes that eliminate the cooling rate gradient, such as 3D additive manufacturing, ultrasonic production, and mold design, combined with the concept of “entropy control” component design and the economic theory of “balanced development,” lead to a three-dimensional bulk amorphous alloy being proposed. The theory of balanced growth provides a new concept for the development and application of bulk amorphous alloys. This review offers a retrospective view of recent studies of amorphous alloys and provides a description of the formation of amorphous alloys and amorphous phases and the criteria required to predict the successful formation of amorphous alloys. Then, we address the problem of size limitation confronting current production methods. The three-dimensional balanced growth theory of bulk amorphous alloys was formulated from a flexible adaptation of the balanced growth theory of economics. We have confidence that the production and development of bulk amorphous alloys have a bright future.

scholarly journals Development of Precipitation Hardening Parameters for High Strength Alloy AA 7068

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 918
Author(s):  
Julia Osten ◽  
Benjamin Milkereit ◽  
Michael Reich ◽  
Bin Yang ◽  
Armin Springer ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Cooling Rate ◽  
Maximum Yield ◽  
High Strength ◽  
Tensile Tests ◽  
Age Hardening ◽  
Scanning Calorimetry ◽  
Cooling Rates ◽  
Critical Cooling Rate ◽  
Kinetics Of

The mechanical properties after age hardening heat treatment and the kinetics of related phase transformations of high strength AlZnMgCu alloy AA 7068 were investigated. The experimental work includes differential scanning calorimetry (DSC), differential fast scanning calorimetry (DFSC), sophisticated differential dilatometry (DIL), scanning electron microscopy (SEM), as well as hardness and tensile tests. For the kinetic analysis of quench induced precipitation by dilatometry new metrological methods and evaluation procedures were established. Using DSC, dissolution behaviour during heating to solution annealing temperature was investigated. These experiments allowed for identification of the appropriate temperature and duration for the solution heat treatment. Continuous cooling experiments in DSC, DFSC, and DIL determined the kinetics of quench induced precipitation. DSC and DIL revealed several overlapping precipitation reactions. The critical cooling rate for a complete supersaturation of the solid solution has been identified to be 600 to 800 K/s. At slightly subcritical cooling rates quench induced precipitation results in a direct hardening effect resulting in a technological critical cooling rate of about 100 K/s, i.e., the hardness after ageing reaches a saturation level for cooling rates faster than 100 K/s. Maximum yield strength of above 600 MPa and tensile strength of up to 650 MPa were attained.

The forming and crystallization behaviors of Zr50Ti5Cu27Ni10Al8 bulk amorphous alloy by laser additive manufacturing

2020 ◽  
Vol 10 (7) ◽  
pp. 1155-1160 ◽  
Author(s):  
Yaqiong Ge ◽  
Xin Chen ◽  
Zexin Chang
Keyword(s):  
Amorphous Alloy ◽  
Cooling Rate ◽  
Heat Affected Zone ◽  
Molten Pool ◽  
Amorphous Structure ◽  
Bulk Amorphous Alloy ◽  
Preparation Process ◽  
Laser Additive Manufacturing ◽  
Obvious Effect ◽  
Composition And Structure

Due to the small size and serious crystallization, the wider application of amorphous alloy materials is limited. In this paper, the bulk amorphous alloy with the size of 15 mm × 15 mm × 12 mm was made by selective laser melting technology. The characters of the composition and structure of the as-prepared bulk amorphous alloy and the thermal effect of the preparation process were analyzed. The results showed that the cooling rate of both the molten pool and the heat affected zone were much higher than the critical cooling rate of the amorphous alloy and, therefore, the cooling rate was not the reason for the crystallization in this experiment. The molten pool of the formed amorphous alloy block was completely amorphous. Due to the accumulation of structural relaxation, crystallization occurred in the heat affected zone, but the amorphous structure was still dominant. The increase in deposition layer had no obvious effect on crystallization.

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