Time evolution of the structural short-range order during the mechanical milling of Fe–Co–Cu nanocrystalline alloys

1999 ◽  
Vol 14 (10) ◽  
pp. 3882-3888 ◽  
Author(s):  
N. Gay-Sanz ◽  
C. Prieto ◽  
A. Muñoz-Martín ◽  
A. de Andrés ◽  
M. Vázquez ◽  
...  

The local order around Fe, Co, and Cu atoms was investigated by extended x-ray absorption fine structure spectroscopy in Fe–Co–Cu nanocrystalline alloys prepared by mechanical alloying. In order to study the time evolution of the alloying process, Fe30Co20Cu50 samples were studied after several processing times. The analysis of the data shows that, in a first step, a binary Co–Cu alloy is formed, but iron remains separate in the form of nanocrystals with a high defect concentration. Afterwards, in a second step, the final ternary Fe–Co–Cu alloy with the face-centered-cubic structure is obtained.

Author(s):  
F. Monchoux ◽  
A. Rocher ◽  
J.L. Martin

Interphase sliding is an important phenomenon of high temperature plasticity. In order to study the microstructural changes associated with it, as well as its influence on the strain rate dependence on stress and temperature, plane boundaries were obtained by welding together two polycrystals of Cu-Zn alloys having the face centered cubic and body centered cubic structures respectively following the procedure described in (1). These specimens were then deformed in shear along the interface on a creep machine (2) at the same temperature as that of the diffusion treatment so as to avoid any precipitation. The present paper reports observations by conventional and high voltage electron microscopy of the microstructure of both phases, in the vicinity of the phase boundary, after different creep tests corresponding to various deformation conditions.Foils were cut by spark machining out of the bulk samples, 0.2 mm thick. They were then electropolished down to 0.1 mm, after which a hole with thin edges was made in an area including the boundary


2009 ◽  
Vol 18 (08) ◽  
pp. 1159-1173 ◽  
Author(s):  
CASEY MANN ◽  
JENNIFER MCLOUD-MANN ◽  
RAMONA RANALLI ◽  
NATHAN SMITH ◽  
BENJAMIN MCCARTY

This article concerns the minimal knotting number for several types of lattices, including the face-centered cubic lattice (fcc), two variations of the body-centered cubic lattice (bcc-14 and bcc-8), and simple-hexagonal lattices (sh). We find, through the use of a computer algorithm, that the minimal knotting number in sh is 20, in fcc is 15, in bcc-14 is 13, and bcc-8 is 18.


1976 ◽  
Vol 31 (12) ◽  
pp. 1539-1542 ◽  
Author(s):  
H. M. Ledbetter

Abstract The Poisson ratio υ of a polycrystalline aggregate was calculated for both the face-centered cubic and the body-centered cubic cases. A general two-body central-force interatomatic potential was used. Deviations of υ from 0.25 were verified. A lower value of υ is predicted for the f.c.c. case than for the b.c.c. case. Observed values of υ for twenty-three cubic elements are discussed in terms of the predicted values. Effects of including volume-dependent electron-energy terms in the inter-atomic potential are discussed.


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