Special Features of Creep-Crack Propagation in Refractory Nickel Alloys under Static Loading

We study creep-crack growth rate in standard specimens of alloys ÉP742 and ÉP962 at a temperature of 973 K under static loading. It is demonstrated that the alloys, which are close in chemical composition and mechanical properties, differ in creep-crack growth resistance.     

Time-temperature section of the phase diagram of the Al−Sc−Zr system at 500°C

The prospects for the use of scandium and zirconium for alloying aluminum alloys with the aim of increasing their high-temperature strength make it necessary to investigate the interaction between aluminum and these metals. The present work is devoted to a study of phase equilibria in the Al−Sc−Zr system at 500°C by methods of physico-chemical analysis and of the effect of a third component on the principal characteristics of binary intermetallic compounds. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 5, pp. 29–30, May, 1997.     

A calculation-experimental study of crack-tip opening displacement and residual stresses upon warm prestressing

For a reactor pressure vessel steel 15Kh2MFA(III) experiments and calculations have been carried out to study the factors that have an influence on the increase of the lower-shelf fracture toughness in the temperature dependence diagrams upon warm prestressing. Stereoscopic fractography and numerical investigation have demonstrated that after the warm prestressing the crack tip remains blunt. This reduces the stress singularity during subsequent loading and raises the material fracture toughness. The paper gives the calculated data on residual stresses and crack-tip opening displacement during warm prestressing and upon relief. The calculated results are shown to agree well with the known analytical relations and experimental data.     

Reduction of the distortion of diffractive-gradient-index high-resolution objectives

The possibility of multiple reductions of the distortion of high-resolution monochromats that consist of diffractive and radial gradient-index lenses is shown. The desirable effect is achieved by mutual compensation of various order members. Design parameters and the field performances of objectives that confirm the effectiveness of a method, are presented.