Amorphization of Nanolaminates during Severe Plastic Deformation: Molecular Simulations in the Cu-Zr System

2003 ◽  
Vol 778 ◽  
Author(s):  
Alan C. Lund ◽  
Christopher A. Schuh

AbstractMechanical alloying techniques, which use plastic deformation to effect structural changes, are commonly used to prepare nanostructured metals with exemplary mechanical properties. When these nanostructured metals are subjected to further straining fully amorphous alloys can result, but there is little understanding of the atomic-scale mechanisms behind this amorphization. In the present work, we explore the final stages of such a mechanical alloying process via molecular simulations. Initial Cu-Zr nanolaminates are sequentially strained and consolidated, and the amorphization process is followed explicitly. The results are in qualitative agreement with existing experimental data, and provide insight into experimentally inaccessible features of the structural evolution.

2009 ◽  
Vol 94 (23) ◽  
pp. 231904 ◽  
Author(s):  
Wei Li ◽  
Xiaohong Li ◽  
Defeng Guo ◽  
Kiminori Sato ◽  
Dmitry V. Gunderov ◽  
...  

MRS Bulletin ◽  
2006 ◽  
Vol 31 (9) ◽  
pp. 669-674 ◽  
Author(s):  
J.K. Nørskov ◽  
M. Scheffler ◽  
H. Toulhoat

AbstractSolid surfaces are used extensively as catalysts throughout the chemical industry, in the energy sector, and in environmental protection. Recently, density functional theory has started providing new insight into the atomic-scale mechanisms of heterogeneous catalysis, helping to interpret the large amount of experimental data gathered during the last decades. This article shows how density functional theory can be used to describe the state of the surface during reactions and the rate of catalytic reactions. It will also show how we are beginning to understand the variation in catalytic activity from one transition metal to the next. Finally, the prospects of using calculations to guide the development of new catalysts in industry will be discussed.


Author(s):  
José Luis Iturbe-García ◽  
Manolo Rodrigo García-Núñez ◽  
Beatriz Eugenia López-Muñoz

Mg2Ni was synthesized by a solid state reaction from the constituent elemental powder mixtures via mechanical alloying. The mixture was ball milled for 10 h at room temperature in an argon atmosphere. The high energy ball mill used here was fabricated at ININ. A hardened steel vial and three steel balls of 12.7 mm in diameter were used for milling. The ball to powder weight ratio was 10:1. A small amount of powder was removed at regular intervals to monitor the structural changes. All the steps were performed in a little lucite glove box under argon gas, this glove box was also constructed in our Institute. The structural evolution during milling was characterized by X-ray diffraction and scanning electron microscopy techniques. The hydrogen reaction was carried out in a micro-reactor under controlledconditions of pressure and temperature. The hydrogen storage properties of mechanically milled powders were evaluated by using a TGA system. Although homogeneous refining and alloying take place efficiently by repeated forging, the process time can be reduced to one fiftieth of the time necessary for conventional mechanical milling and attrition.        


2004 ◽  
Vol 375-377 ◽  
pp. 881-887 ◽  
Author(s):  
J.J. Suñol ◽  
A. González ◽  
T. Pradell ◽  
P. Bruna ◽  
M.T. Clavaguera-Mora ◽  
...  

2013 ◽  
Vol 275-277 ◽  
pp. 1751-1754
Author(s):  
Zhang Jing ◽  
Qi Zhi Cao ◽  
Zheng Liang Li

Nanostructured Al-25at.%Fe-5at.%Ni intermetallics were prepared directly by mechanical alloying (MA) in a high-energy planetary ball-mill. The phase transformations and structural changes occurring in the studied material during mechanical alloying were investigated by X-ray diffraction (XRD). Scanning electron microscopy (SEM) was employed to examine the morphology of the powders. Thermal behavior of the milled powders was examined by differential thermal analysis (DTA). The solid solutions of Fe (Al) and Ni (Fe) in the Al70Fe25Ni5 system are observed at the early milling stage. The solid solutions transforms into amorphous and disordered Al (Fe, Ni) phase. The last milling products in the Al70Fe25Ni5 system are Al3Ni2, AlFe3 and AlFe0.23Ni0.77 phases.


2012 ◽  
Vol 476-478 ◽  
pp. 1476-1479
Author(s):  
Qi Zhi Cao ◽  
Jing Zhang ◽  
Jian Ying Li

Nanostructured Fe25Al50Ni25intermetallics was prepared directly by mechanical alloying (MA) in a high-energy planetary ball-mill. The phase transformations and structural changes occurring in the studied material during mechanical alloying were investigated by X-ray diffraction (XRD). Thermal behavior of the milled powders was examined by differential thermal analysis (DTA). Disordered Al(Fe,Ni) solid solution was formed After 50 h of milling. Al(Fe,Ni) solid solution milled for 100h transformed into FeNi,FeNi3 and AlNi3 phase. The power annealed at temperature 500 results in forming of intermetallics AlFe0.23Ni0.77, Al1.1Ni0.9 , AlNi and two unknown phase after 5h milling. The nanocrystalline metallic compound was obtained after 100h milling.


Author(s):  
T. Santos ◽  
C.S.F. Gomes ◽  
L. Hennetier ◽  
V.A.F. Costa ◽  
L.C. Costa

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

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