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High dose and intense implantation of the multiply charged Al plus n, Ti plus n and C plus n into alfa-iron

: Pogrebnjak, A.D.; Bakharev, O.G.; Martynenko, V.A.; Rudenko, V.A.; Brusa, R.; Zecca, A.; Ryssel, H.; Tikhomirov, I.A.; Ryabchikov, A.I.; Öchsner, R.


Nuclear instruments and methods in physics research, Section A. Accelerators, spectrometers, detectors and associated equipment 94 (1994), S.81-90
ISSN: 0167-5087
ISSN: 0168-9002
Fraunhofer IIS B ( IISB) ()
aluminium; carbon; concentration profile; friction; ion implantation; iron; micro hardness; Mössbauer spectroscopy defect; multiply changed ion; titanium; wear

The "long range effect", i.e. the formation of a layer with an elevated concentration of defects of non-crystalline structure at depths significantly exceeding the ion ranges (by more than 1-3 orders of magnitude) has not been found in the case of high dose (up to 8 x 10 high17 ions/qcm) intensive implantation of alpha-Fe with titanium, aluminium and carbon ions. Titanium implantation of alpha-Fe is characterized by the formation of a defect layer including: vacancy clusters, complexes: vacancy plus impurity atoms localized in the region to 50 nm from the surface and secondary defects: loops and dislocations, which could be found at a depth of to 250-400 nm from the surface (depending on the irradiation dose). The maximum depth of Ti ion range in alpha-Fe for high irradiation dose of 5 x 10 high17 ions/qcm is 92 nm, which is commensurable with a layer of increased defect concentration (300 to 350 nm) in the order of magnitude. Increasing the irradiation dose to 5 x 10 high17 ions/qcm ( Ti irradiation of alpha-Fe) results in the intensification of titanium carbide formation process (TiC) caused carbon doped from the residual atmosphere of the accelerator chamber. Formation of small dispersion carbides results in deceleration of dislocations, a dense network of which appears in the near surface layer due to high local strains in microasperities and, likely to draw impurities into material bulk. This seems to result in decreased material ablation in friction tests. The formation of small dispersion titanium carbides (and, likely, thin film of oxicarbides at the surface) results in decreased friction coefficient after high dose implantation of alpha-Fe with titanium ions in comparison with the initial alpha-Fe. The doping of Al ions into alpha-Fe results in the formation of an ordered magnetic phase Fe sub3 Al with further ordering. The increased implantation dose of Al into alpha-Fe to 5 x 10 high17 ions/qcm results in a decreased degree of ordering and possibly, parti a l amorphization. In this case, we observed wear reduction was a factor of 2 after two hours. The maximum depth of the layer with increased concentration of defects with crystalline structure in aluminium implanted alpha-Fe does not exceed 300 nm for a maximum depth of Al ion range in alpha-Fe (200 nm) even with the dose of 5 x 10 high17 ions/qcm. Doping of carbon ions in iron results in enhanced carbon concentration in solid solution, and in the case of the implementation dose 2 x 10 high17 ions/qcm, it results in E-carbide formation (Fe sub2 C), which then partially transforms into cementite (Fe sub3 C) due to substrate heating caused by irradiation. Increased implantation dose in the case of carbon irradiation of alpha-Fe results in a significant microhardness increase of irradiation samples, but does not result in remarkable wear decrease in dry friction tests. The maximum depth of the defect containing layer in the case of carbon high dose implantation (to 5 x 10 high17 ions/qcm) o f alpha-Fe does not exceed 300 nm when the depth of singly charged carbon ions is a maximum (200 nm).