scholarly journals Effect of Niobium and Yttrium Modified Ti-Based Bulk Amorphous Alloy on Correlation of Plastic Deformation Energy and Ductility

Author(s):  
Shengfeng Shan ◽  
Bing Zhang ◽  
Yuanzhi Jia ◽  
Mingzhen Ma

A series of Ti40Zr25Cu9Ni8Be18)100-xTMx (x = 0, 1, 2, 3, 4 at.%, TM = Nb, Y) Bulk amorphous alloys were designed and prepared using the copper mold casting method. The microstructures, glass forming ability and mechanical properties of the alloys were investigated by means of X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning colorimetry (DSC), depth-sensitive nanoindentation and uniaxial compressive test. The Bulk amorphous alloys with different ductility were investigated by measuring their plastic deformation energy (PDE) of the first pop-in events during loading. The relationships between the PDE value, shear band formation and ductility in Bulk amorphous alloys have been investigated. The results show that the PDE value decreases by the Nb addition and promotes the generation of multiple shear bands easily, which increase the fracture strength and plasticity significantly. Substituting Nb with Y has exactly the reverse effect. A useful rule for preparing of Bulk amorphous alloys with high plasticity is herein proposed, whereby the chemical composition of the Bulk amorphous alloys can be tailored to possess a lower PDE value.

2007 ◽  
Vol 22 (2) ◽  
pp. 486-492 ◽  
Author(s):  
Seok-Woo Lee ◽  
Sang-Chul Lee ◽  
Yu-Chan Kim ◽  
E. Fleury ◽  
Jae-Chul Lee

We synthesized bulk amorphous alloy systems of Cu43Zr43Al7X7 (X = Be, Ag; numbers indicate at.%), with the objective of simultaneously enhancing the glass-forming ability (GFA) and the plasticity. The alloys not only exhibit high plasticity (∼7%, ∼8%), but also possess enhanced GFA (alloys with 12 and 8 mm diameter). The possible mechanisms underlying this enhanced GFA and plasticity exhibited by these alloys are discussed based on the atomic-packing state and atomistic-scale compositional separation associated with the mixing enthalpy difference. A strategy for designing bulk amorphous alloys with simultaneous improvement in the GFA and the plasticity is proposed from the viewpoint of atomic-packing state and atomistic-scale phase separation.


China Foundry ◽  
2021 ◽  
Vol 18 (1) ◽  
pp. 60-67
Author(s):  
Sheng-feng Shan ◽  
Hao Wang ◽  
Bing Zhang ◽  
Yuan-zhi Jia ◽  
Ming-zhen Ma

1993 ◽  
Vol 321 ◽  
Author(s):  
H. Chen ◽  
Y. He ◽  
G. J. Shiflet ◽  
S. J. Poon

ABSTRACTWe report the first direct observation of crystallization induced in the slipped planes of aluminum based amorphous alloys by bending the amorphous ribbons. Nanometer-sized crystalline precipitates are found exclusively within a thin layer (shear band) in the slipped planes extending across the deformed amorphous alloy ribbons. It is also found that the nanocrystalline aluminum can be produced by ball-Milling. It is likely that local atomic rearrangements within the shear bands create the nanocrystals which appear after plastic deformation.


2003 ◽  
Vol 18 (4) ◽  
pp. 755-757 ◽  
Author(s):  
W. H. Jiang ◽  
M. Atzmon

Plastic deformation of amorphous Al90Fe5Gd5 was investigated using nanoindentation and atomic force microscopy. While serrated flow was detected only at high loading rates, shear bands were observed for all loading rates, ranging from 1 to 100 nm/s. However, the details of shear-band formation depend on the loading rate.


2015 ◽  
Vol 1120-1121 ◽  
pp. 440-445
Author(s):  
Hua Man

The glass forming ability and magnetic properties were investigated for adding neodymium to the Fe71-xNb4B25Ndx (x=0, 3, 5, 7,10) alloys prepared by copper suction casting. It was found that proper neodymium (x=5~10 at.%) could improve glass forming ability of Fe-Nb-B alloys effectively. Bulk amorphous Fe66Nd5B25Nb4 and Fe64Nd7B25Nb4 samples were obtained and presented high thermal stability and good soft magnetic properties. The value of activation energy of the first crystallization peak for the bulk amorphous alloy Fe64Nd7B25Nb4 is 683 kJ/mol.


2014 ◽  
Vol 783-786 ◽  
pp. 27-32 ◽  
Author(s):  
Leszek Adam Dobrzański ◽  
Wojciech Borek ◽  
Janusz Mazurkiewicz

Taking into consideration increased quantity of accessories used in modern cars, decreasing car’s weight can be achieved solely by optimization of sections of sheets used for bearing and reinforcing elements as well as for body panelling parts of a car. Application of sheets with lower thickness requires using sheets with higher mechanical properties, however keeping adequate formability. The goal of structural elements such as frontal frame side members, bumpers and the others is to take over the energy of an impact. Therefore, steels that are used for these parts should be characterized by high value of UTS and UEl, proving the ability of energy absorption. Among the wide variety of recently developed steels, high-manganese austenitic steels with low stacking faulty energy are particularly promising, especially when mechanical twinning occurs. Beneficial combination of high strength and ductile properties of these steels depends on structural processes taking place during cold plastic deformation, which are a derivative of SFE of austenite, dependent, in turn on the chemical composition of steel and deformation temperature. High-manganese austenitic steels in effect of application of proper heat treatment or thermo-mechanical treatment can be characterized by different structure assuring the advantageous connection of strength and plasticity properties. Proper determinant of these properties can be plastic deformation energy supply determined by integral over surface of cold plastic deformation curve. Obtaining of high strength properties with retaining the high plasticity has significant influence for the development of high-manganese steel groups and their significance for the development of materials engineering.


Author(s):  
Anil K. Sachdev ◽  
M. M. Shea

In a recent study, the mechanical behavior of an Fe-15 Ni-0.8 C austenite was determined at various strain rates and temperatures. An important finding of this study was the formation of intense shear bands during deformation at temperatures much greater than which bore no resemblance to the common morphologies of martensites. There is much disagreement in the literature regarding the mechanism of band formation and the associated substructure. These bands have been reported to be fine BCC martensite particles or laths delineating slip bands or thin twins in the austenite matrix. The purpose of the present work was to determine by transmission electron microscopy and diffraction the substructure of the fine bands and to attempt to clarify the various interpretations. For comparison, the substructure produced at a lower deformation temperature was also evaluated where the martensite was known to have the normal strain-induced morphology.


2015 ◽  
Vol 1110 ◽  
pp. 136-141 ◽  
Author(s):  
Beom Taek Jang ◽  
Young In Kim

For enhancing wear property of Fe-based bulk amorphous alloys as structural materials, We investigate effects of Cr or Mo compositions on wear and mechanical behaviors of FeCSiBPMo and FeCSiBPAlCr system bulk amorphous alloys which are suction-cast into a copper mold by arc melting in an argon atmosphere using a suction casting technique. X-ray diffraction, differential scanning calorimeter and Scanning electron microscopy were used to observe the microstructure and surface morphologies. Cr-Fe or Mo-Fe substitutions led to a dramatic increase in the glass transition temperature as well as the supercooled liquid region. After the wear test, the mass loss of both BAAs decreased remarkably at higher element. Nanoindentation results indicate that with an increase of the Cr or Mo compositions, the hardness and elastic modulus increased in both BAA samples. These results suggest that wear behaviors of the BAAs corresponded to change in hardness, which means that fracture morphologies of worn surface are strongly dependent on surface hardening with high Cr or Mo content.


2010 ◽  
Vol 165 ◽  
pp. 226-230
Author(s):  
Sylwia Wiewiórowska ◽  
Zbigniew Muskalski ◽  
Maciej Suliga

The development of new technologies of metal joining processes including brazing methods requires improvement of solder properties. Copper-based brazing solders with phosphorus and tin additions belong to the group of silver-free brazing alloys with low ductility. The most common form of these solders are bars and wires so there is a need to determine the causes of technological problems concerned with plastic deformation of the solders. In the literature, except for the chemical composition and temperature of brazing, we can not find the details regarding the change of solder structure during heating processes. The preliminary tests carried out in the industry indicate high plasticity of solder in the narrow range of temperature. This encouraged the authors of the paper to perform dilatometric testing with the aim of establishing the precise temperatures of solder phase changes. The metallographic research with the use of scanning electron microscopy enabled the determination of phase composition of “freezing” structures and the evaluation of their flexibility to the plastic deformation.


2006 ◽  
Vol 519-521 ◽  
pp. 1047-1052 ◽  
Author(s):  
Mohammad Jaffar Hadianfard ◽  
Michael J. Worswick

The effect of strain rate in the range of 10-4 to 10-1 s-1 on localization of deformation and fracture behavior of 5754 and 5182 aluminum alloys is investigated. For this study, tensile tests, interrupted tensile tests, shear band decoration, fractography and image analysis has been used. This investigation is based on experimental work and observation of the material behavior. Results show that strain rate has some effect on the mechanical properties and deformation stability of the alloys. The area of localized plastic deformation and thickness of the shear bands were found to be sensitive to the strain rate. It was also observed that localization of plastic deformation and shear band formation is an important step in the damage propagation and final fracture of the alloys. Detail of damage development, based upon micrographs of samples interrupted at different stages of straining is presented


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