Formation of hardened surface layers in titanium under irradiation with intense ion beams

2001 ◽  
Vol 44 (4) ◽  
pp. 625-630 ◽  
Author(s):  
V Lavrentiev ◽  
C Hammerl ◽  
B Rauschenbach ◽  
O Kukharenko
2021 ◽  
Vol 102 (2) ◽  
pp. 50-55
Author(s):  
S.А. Ghyngаzоv ◽  
◽  
V.А. Kоstenkо ◽  
S.V. Matrenin ◽  
A.I. Kupchishin ◽  
...  

The paper investigated modification of the microstructure of the surface layers of alumina ceramics under exposure to electron and ion beams. Electron beam irradiation was performed at accelerating voltage U = 15 kV and beam current of J = 70 A and J = 100 A. Ion irradiation was performed with carbon ions at accelerating voltage of U = 180 keV. The current density and energy density varied in the range of 15–85 A/cm2 and 0.3–1.5 J/cm2 , respectively. The amount of energy acting on the ceramic surface depended on the number of pulses N. It is shown that exposure to electron and ion beams changes the microstructure of the irradiated ceramic layer. In general, the effect of exposure is similar for electron and ion irradiation, and it is characterized not only by surface melting, but also by formation of a finer microstructure through the depth of the irradiated layer, which is oriented in the direction of the electron and ion beam exposure. It is shown that crystallization processes in overheated layers of ceramics depend on its type and melting point.


2002 ◽  
Vol 158-159 ◽  
pp. 170-173 ◽  
Author(s):  
A.V Petrov ◽  
A.I Ryabchikov ◽  
I.B Stepanov ◽  
V.K Struts ◽  
N.M Polkovnikova ◽  
...  

It is well known that even under very heavy loads the hills on rough surfaces are not completely flattened. Many workers have advanced possible reasons for this remarkable persistence of the surface asperities. The most commonly advocated mechanisms are examined, and it is demonstrated that none of them provides an adequate explanation of the phenomenon. The plastic indentation of a flat by a hard ball is then studied, and the real area of contact is measured directly using high resolution profilometry. It is concluded that asperity persistence does not depend on the particular metal in contact. Nor is it an intrinsic property of the individual hills on the surface; there is no evidence that work hardening during the crushing of asperities can form a hardened surface layer which leads to a smaller contact area, as is commonly supposed. It is shown that, for local indentations, the degree of contact, i. e. the ratio of real to nominal area, is in general independent of the load. Whenever the surface layers are harder than the bulk the degree of contact is typically between one quarter and one third. However, when the indented body has a uniform hardness the degree of contact was found to be accurately equal to one-half.


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