Fracture at elevated temperature

Intermediate Temperature Embrittlement of Dispersion Hardened Cu&ndash;GeO<SUB>2</SUB> Polycrystals

“…1 appeared to show ductile fracture, the gradual growth of intergranular cracks actually took place during deformation and the fractured specimens showed no apparent reduction in the cross-sectional area. Such disappearance of recrystallization and occurrence of intergranular brittle fracture at higher temperatures have also been reported by Pavinich and Raj for a Cu-SiO2 alloy system (9). Although little is known, these phenomena are believed to be characteristic of dispersion-hardened polycrystals.…”

“…Pavinich and Raj studied the temperature and strainrate dependence of high-temperature deformation and fracture behavior of Cu-Si02 dispersion-hardened alloy (9). However, their interest was limited to the temperature range above 673 K (about 0.5 Tm, Tm: the melting point) and, as far as the present authors know, no detailed investigation of copper-base disper-sion hardened alloys has been reported for an intermediate temperature range between room temperature (about 0.2Tm) and 0.5Tm.…”

High temperature behavior of Ni-base weld metal

“…The creep resistance of stainless steels and Ni-base alloys increases with the addition of C and other strong MC carbide forming elements as Nb, Ti and V is well known [50]. The C effect is so important that decarburization on the sample surface during creep testing have resulted in a reduction of creep resistance and life of the Ni-base alloy Inconel 617 [29]. However, the reports regarding the effect of carbon on the hot cracking of Ni-base alloys are contradictory, which reveals the complexity of this element's effect.…”

“…But even during this final stage of creep life, the carbides may improve the material response reducing the agglomeration of voids, as observed in some cast stainless steels [28]. The deformation concentration around intergranular precipitates promotes void nucleation [13,29] by second phase/matrix interface separation [11,30] or failure of the precipitate itself, which then propagates into the matrix [9,31]. Continuous carbides along the GB are easy crack propagation paths [32].…”

Tensile creep fracture of polycrystalline near-stoichiometric NiAl

“…The values of C MG vary between 1.8 and 38 for many metals and alloys [22]. The Monkman-Grant constant can be broadly interpreted as a simple measure of creep ductility since it ignores strain contributions from primary and tertiary creep [26,27]. Monkman and Grant [22] associated low values of C MG with intergranular fracture, where the secondary creep stage lasted much longer than the primary and the tertiary creep stages.…”