High dose self-ion irradiation of silicon carbide with nanostructured ferritic alloy aid

ABSTRACTA novel atom probe tomography (APT) method has been developed that enables a full description of the orientation relationship between individual grains to be determined together with estimates of the extents of solute segregation for all elements over the surface of the grain boundary with 1 nm by 1 nm spatial resolution. This approach also enables variations in the solute excess for the elements with the habit plane and curvature of the grain boundary to be evaluated. The method has been applied to a mechanically-alloyed nanostructured ferritic alloy (NFA) after high dose heavy ion irradiation. The innovative high-resolution two-dimensional mapping of the solute segregation across the surface of grain boundaries in the NFA clearly demonstrates that the distributions of chromium and tungsten are not uniform across the grain boundaries, and the distributions correlate with changes in its local curvature and the position of the grain boundary precipitates. These features pin the grain boundary against grain growth and provide the stability for excellent creep properties.

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Effect of Ion Irradiation on Nanoindentation Fracture and Deformation in Silicon Carbide

JOM ◽

10.1007/s11837-021-04636-8 ◽

2021 ◽

Author(s):

Alexander J. Leide ◽

Richard I. Todd ◽

David E. J. Armstrong

Keyword(s):

Mechanical Properties ◽

Silicon Carbide ◽

Residual Stresses ◽

Focused Ion Beam ◽

Electron Backscatter Diffraction ◽

Ion Irradiation ◽

Ion Beam ◽

Resolution Electron ◽

Radiation Induced ◽

Compressive Residual Stresses

AbstractSilicon carbide is desirable for many nuclear applications, making it necessary to understand how it deforms after irradiation. Ion implantation combined with nanoindentation is commonly used to measure radiation-induced changes to mechanical properties; hardness and modulus can be calculated from load–displacement curves, and fracture toughness can be estimated from surface crack lengths. Further insight into indentation deformation and fracture is required to understand the observed changes to mechanical properties caused by irradiation. This paper investigates indentation deformation using high-resolution electron backscatter diffraction (HR-EBSD) and Raman spectroscopy. Significant differences exist after irradiation: fracture is suppressed by swelling-induced compressive residual stresses, and the plastically deformed region extends further from the indentation. During focused ion beam cross-sectioning, indentation cracks grow, and residual stresses are modified. The results clarify the mechanisms responsible for the modification of apparent hardness and apparent indentation toughness values caused by the compressive residual stresses in ion-implanted specimens.

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Mechanical and Corrosion Properties of VT6 Titanium Alloy after Irradiation with Helium and Aluminum Lons

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.887.229 ◽

2021 ◽

Vol 887 ◽

pp. 229-234

Author(s):

Viktor V. Ovchinnikov ◽

Svetlana V. Yakutina ◽

Nadezhda V. Uchevatkina

Keyword(s):

Titanium Alloy ◽

Ion Irradiation ◽

Structural Phase ◽

High Dose ◽

Corrosion Properties ◽

Average Grain Size ◽

Aluminum Implantation ◽

Modified Surface ◽

Mechanical And Corrosion Properties ◽

Mechanical Properties And Corrosion

The effect of high-dose aluminum implantation on the structural-phase state of the surface layer of titanium alloy VT6 with a fine structure (average grain size 2.3 μm) on the mechanical and corrosion properties has been investigated. It is shown that, as a result of ion irradiation, polyphase implanted layers based on α-titanium grains are formed, containing an intermetallic Ti3Al phase along the grain boundaries of α-titanium. The modified surface layers are characterized by improved mechanical properties and corrosion resistance. The noted effect is enhanced by the use of preliminary helium implantation with a dose of 1.3 × 1017 ion / cm2.

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Strain/Damage in Crystalline Materials Bombarded by MeV Ions: Recrystallization of GaAs by High-Dose Irradiation

MRS Proceedings ◽

10.1557/proc-35-305 ◽

1984 ◽

Vol 35 ◽

Cited By ~ 11

Author(s):

C. R. Wie ◽

T. Vreeland ◽

T. A. Tombrello

Keyword(s):

Surface Layer ◽

Energy Loss ◽

Ion Irradiation ◽

Stopping Power ◽

High Dose ◽

Double Crystal ◽

Saturation Phenomenon ◽

Nuclear Stopping ◽

X Ray ◽

Dose Irradiation

ABSTRACTMeV ion irradiation effects on semiconductor crystals, GaAs(100) and Si (111) and on an insulating crystal CaF2 (111) have been studied by the x-ray rocking curve technique using a double crystal x-ray diffractometer. The results on GaAs are particularly interesting. The strain developed by ion irradiation in the surface layers of GaAs (100) saturates to a certain level after a high dose irradiation (typically 1015/cm2), resulting in a uniform lattice spacing about 0.4% larger than the original spacing of the lattice planes parallel to the surface. The layer of uniform strain corresponds in depth to the region where electronic energy loss is dominant over nuclear collision energy loss. The saturated strain level is the same for both p-type and n-type GaAs. In the early stages of irradiation, the strain induced in the surface is shown to be proportional to the nuclear stopping power at the surface and is independent of electronic stopping power. The strain saturation phenomenon in GaAs is discussed in terms of point defect saturation in the surface layer.An isochronal (15 min.) annealing was done on the Cr-doped GaAs at temperatures between 200° C and 700° C. The intensity in the diffraction peak from the surface strained layer jumps at 200° C < T ≤ 300° C. The strain decreases gradually with temperature, approaching zero at T ≤ 500° C.The strain saturation phenomenon does not occur in the irradiated Si. The strain induced in Si is generally very low (less than 0.06%) and is interpreted to be mostly in the layers adjacent to the maximum nuclear stopping region, with zero strain in the surface layer. The data on CaF2 have been analysed with a kinematical x-ray diffraction theory to get quantitative strain and damage depth profiles for several different doses.

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