Microstructural aspects of phosphorus grain boundary segregation in low alloy steels

2001 ◽  
Vol 47 (1-2) ◽  
pp. 44-49 ◽  
Author(s):  
J Perháčová ◽  
D Grman ◽  
M Svoboda ◽  
J Patscheider ◽  
A Výrostková ◽  
...  
2003 ◽  
Vol 51 (14) ◽  
pp. 4025-4032 ◽  
Author(s):  
J Janovec ◽  
A Výrostková ◽  
P Ševc ◽  
J.S Robinson ◽  
M Svoboda ◽  
...  

2007 ◽  
Vol 353-358 ◽  
pp. 396-399
Author(s):  
Yu Dong Fu ◽  
Gang Wang ◽  
Chen Liu ◽  
Qing Fen Li

In the present paper, the non-equilibrium grain-boundary segregation of P atom was studied in low alloy steels subjected to a low tensile stress at different temperatures. The AES (Auger electron spectroscopy) experiments and dynamic analyses were conducted to study on the non-equilibrium grain-boundary segregation of P atom. The research results show that non-equilibrium segregation of phosphorus occurred at the grain boundaries of the steels 2.25Cr1Mo and 12Cr1MoV, while the critical time reached about 0-1 hour at constant temperatures 773 and 813K. The relationship between the diffusion rate and the diffusion time for the complex and the phosphorus atom was investigated based on the experimental results. Eventually the diffusion coefficients of complex and P were calculated with using a proposed dynamic model.


2000 ◽  
Vol 30 (1) ◽  
pp. 354-358 ◽  
Author(s):  
J. Janovec ◽  
D. Grman ◽  
J. Perh�?ov� ◽  
P. Lej?ek ◽  
J. Patscheider ◽  
...  

1999 ◽  
Vol 70 (7) ◽  
pp. 269-273 ◽  
Author(s):  
Jozef Janovec ◽  
Anna Výrostková ◽  
Jana Perhácová ◽  
Viera Homolová ◽  
Hans Jürgen Grabke ◽  
...  

Equilibrium segregation of Groups IV-VI residual elements during heat treatment ( ca . 773K) of commercial low alloy steels can significantly modify their toughness, impact properties, corrosion and stress corrosion behaviour and creep life. Since these segregations are highly localized (less than about 10 nm) and do not result in microstructural changes, their direct measurement has proved difficult. The most widely used method to date is Auger electron spectroscopy (A.e.s.). This technique is surface specific, requires uncontaminated intergranularly fractured surfaces and is therefore limited by specimen preparation. The development of scanning transmission electron microscopy (s.t.e.m.) with fine electron probes, ca . 15 nm in diameter, when coupled with an energy dispersive analyser enables high resolution X-ray microanalysis within thin foils. This allows grain boundary chemical analysis for elements with atomic number not less than 12. The application of this technique has been investigated by examining segregation of residual elements in experimental iron-based alloys and commercial ferritic steels.


Author(s):  
C.L. Briant

Grain boundary segregation is the process by which solute elements in a material diffuse to the grain boundaries, become trapped there, and increase their local concentration at the boundary over that in the bulk. As a result of this process this local concentration of the segregant at the grain boundary can be many orders of magnitude greater than the bulk concentration of the segregant. The importance of this problem lies in the fact that grain boundary segregation can affect many material properties such as fracture, corrosion, and grain growth.One of the best ways to study grain boundary segregation is with Auger electron spectroscopy. This spectroscopy is an extremely surface sensitive technique. When it is used to study grain boundary segregation the sample must first be fractured intergranularly in the high vacuum spectrometer. This fracture surface is then the one that is analyzed. The development of scanning Auger spectrometers have allowed researchers to first image the fracture surface that is created and then to perform analyses on individual grain boundaries.


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