Determination of the elastic moduli and residual stresses of freestanding Au-TiW bilayer thin films by nanoindentation

P92 steel was irradiated with Ar ion up to 10 dpa at 200, 400, and 700 • C. The effect of Ar ion irradiation on hardness was investigated with nanoindentation tests and microstructure analyses. It was observed that irradiation-induced hardening occurred in the steel after Ar ion irradiation at all three temperatures to 10 dpa. The steel exhibited significant hardening at 200 and 700 • C, and slight hardening at 400 • C under Ar ion irradiation. Difference in the magnitude of irradiation-induced hardening at different temperature in the steel is attributed to different changes in the microstructure of the steel that arose from the irradiation. Irradiation-induced hardening in the P92 steel irradiated at 200 • C is attributed to the occurrence of both dislocation loops and other fine irradiation defects during irradiation. Slight hardening in the steel irradiated at 400 • C mainly arises from the annihilation of defect clusters at this temperature. The occurrence of fine Ar bubbles with high number density during the Ar ion irradiation at 700 • C resulted in the significant hardening in the steel.

Section: Methodsmentioning

confidence: 99%

Evaluation of Irradiation Hardening of P92 Steel under Ar Ion Irradiation

Liu

Shen

Zhu³

et al. 2018

“…The improvement of mechanical properties may be related to the residual stress and fracture toughness at the interface between the Al2O3 and the Al matrix. However, it is very difficult to measure the residual stress and fracture toughness at the interface between the Al2O3 and the Al matrix, and it could be helpful to employ nanoindentation and pillar splitting techniques as reported by Matteo Ghidelli et al [39,40].…”

Section: Influence Of Stirring Temperature and Stirring Time On Mechamentioning

confidence: 99%

Microstructure, Mechanical Properties and Wear Behavior of the Rheoformed 2024 Aluminum Matrix Composite Component Reinforced by Al2O3 Nanoparticles

Jiang

Xiao

Che

et al. 2018

Abstract:The 2024 nanocomposite reinforced with Al 2 O 3 nanoparticles was fabricated by the ultrasonic assisted semisolid stirring (UASS) method and rheoformed into a cylinder component. Microstructure, mechanical properties, and wear behavior of the rheoformed composite components were investigated. The results showed that the composite components with complete filling status and a good surface were rheoformed successfully. The deformation of semisolid slurries was mainly dominated by flow of liquid incorporating solid grains (FLS), sliding between solid grains (SSG), and plastic deformation of solid grains (PDS). Mechanical properties of the rheoformed composite components were influenced by stirring temperature, stirring time, and volume fraction of Al 2 O 3 nanoparticles. The optimal ultimate tensile strength (UTS) of 358 MPa and YS of 245 MPa were obtained at the bottom of the rheoformed composite components after a 25-min stirring of composite semisolid slurry with 5% Al 2 O 3 nanoparticles at 620 • C. Enhancement of mechanical properties was attributed to high density dislocations and dislocation tangles and uniform dispersed Al 2 O 3 nanoparticles in the aluminum matrix. Natural ageing led to the occurrence of needle-like Al 2 CuMg phase and short-rod-like Al 2 Cu phase. UTS of 417 MPa and YS of 328 MPa of the rheoformed composite components were achieved after T6 heat treatment. Improvement of mechanical properties is due to the more precipitated needle-like Al 2 CuMg phase and short-rod-like Al 2 Cu phase. Wear resistance of the rheoformed composite components was higher than that of the rheoformed matrix component. Wear resistance of the rheoformed composite component increased with an increase in Al 2 O 3 nanoparticles from 1% to 7%. A slight decrease in wear rate resulted from 10% Al 2 O 3 nanoparticles due to greater agglomeration of Al 2 O 3 nanoparticles. A combination mechanism of adhesion and delamination was determined according to worn surface morphology.

“…For example, Ghidelli et al [25] evaluated the elastic moduli on thin films considering the effect of residual stress. However, when the residual stress varies with time, as in fatigue crack growth, evaluation of the effects of residual stress often involves complicated stress analysis.…”

Section: Difference In the Fcg Behavior Between Short Surface Cracks mentioning

confidence: 99%

On the Short Surface Fatigue Crack Growth Behavior in a Fine-Grained WC-Co Cemented Carbide

Mikado

Ishihara

Oguma

et al. 2017

Abstract:In the present study, the fatigue crack growth (FCG) behavior of short surface cracks in a fine-grained cemented carbide with a length of less than 1 mm was investigated. The rotating bending and the four-point bending fatigue tests were carried out at stress ratios of R = −1 and R = 0.1 (R = maximum stress/minimum stress). It was found that a short surface crack had a longer stable fatigue crack growth area than a long through-thickness crack; the FCG behaviors of the two types of crack are clearly different. Furthermore, the FCG path of short surface cracks was investigated in detail to study the interaction between fatigue cracks and microstructures of the cemented carbide such as WC grains and the Co phase. At a low K max (K max = the maximum stress intensity factor), it was found that fatigue crack growth within WC grains is difficult because of a small driving force; instead, crack growth is along the brittle WC/WC interface. On the other hand, at a high K max , WC grain breakage often occurs, since the driving force of FCG is large, and the fatigue crack grows linearly.