Reticulated nickel foams were alloyed with chromium by pack-chromizing, resulting in Ni–Cr foams with 9–32 wt.% Cr and 2.6–3.5% relative density. The oxidation resistance at 1000 ◦C of the Ni–Cr foams and the corresponding bulk Ni–Cr alloys is the same, provided the foam’s higher surface area is taken into account. The foam compressive yield stress at ambient temperature is in agreement with mo...

Deformation mechanisms and the role of interfaces in deformation twinning of a two-phase [TiAI (y)GAl (ad] 1 amellar allo\t creep deformed at elevated temperatures have been investigated. Since the multiplication of lattice dislocations \vithin both y and a2 lamellae is verl\’ limited at a lo\v stress level due to a refined lamellar microstructure, the glide of interfacial dislocations on both ...

The high creep resistance of dispersion-strengthened metals is the result of a threshold stress, which is determined in existing models by considering the interaction of a single dislocation with dispersoids. This paper presents a new model which takes into account the effect of dislocation pile-ups upon the detachment threshold stress of dispersion-strengthened metals. First, it is shown that ...

We report the observation of a negative dynamic creep rate, i.e., increasing irreversibility in the magnetic hysteresis loop for decreasing sweep rate of the magnetic field, in both YBa2Cu3O72d and 2H-NbSe2 single crystals. This phenomenon is found to appear on the increasing branch of the peak effect that corresponds to a state which is intermediate between the dislocation-free Bragg glass and...

The aims of this paper were to: (a) demonstrate how iso-thermal plots of the Wilshire equation can be used to identify the correct structure of this equation (which in turn enables a meaningful description of the creep mechanism involved in deformation to be made); and (b) show how a generalized specification of batch to batch variation could produce less conservative predictions of the time to...

The higher steam temperatures and pressures required to achieve an increase in the thermal efficiency of fossil fuel fired power generation plant necessitate the application of steels with improved creep rupture strength. The 9% chromium steels developed during the last three decades are of great interest for components of advanced, high efficiency power plant. In this Paper, the development of...

Dislocations in solids contribute to anelastic attenuation, relaxation of the shear modulus, transient creep, and steady state flow. These properties of the mantle may therefore be related. The glide and climb of dislocations appear to have the appropriate time constants to explain seismic wave attenuation and mantle viscosity, respectively. The dislocation density of the mantle depends on the ...

A spark plasma sintering (SPS) apparatus was used for the first time as an analytical testing tool for studying creep in ceramics at elevated temperatures. Compression creep experiments on a fine-grained (250 nm) polycrystalline magnesium aluminate spinel were successfully performed in the 1100-1200 °C temperature range, under an applied stress of 120-200 MPa. It was found that the stress expon...

Article history: Received 17 May 2013 Accepted 6 August 2013 Available online 16 August 2013 Creep was studied in Haynes 230, a material candidate for the very high temperature reactor’s intermediate heat exchanger, at 800 C and 900 C. This study focused on the differences between the behavior at the two elevated temperature, and using the microstructure, grain boundary serrations and triple ju...