The deformation of zirconium-oxygen single crystals

Grain Breakup During Elevated Temperature Deformation of an HCP Metal

“…Early studies on single crystals showed that the relative activity of the available systems changes with temperature. [27,28] In the current study, the Lankford coefficients measured after compression testing suggest that deformation along the hci axis becomes more difficult as temperature increases. The simplest explanation for this behavior is that hc+ai slip becomes relatively harder than prismatic and basal slip (hai slip).…”

“…Therefore, the dramatic drop in flow stress with increasing temperature is likely to be caused by the temperature sensitivity of prismatic hai slip, which is well known and has been attributed to a number of phenomena, including the change in strength of solute pinning [28,31] or even simply to the variation of the lattice resistance to slip. [32] The changes in Lankford coefficient with temperature shown in Figure 3 suggest that the difference in CRSS between hai and hc+ai slip increases with the temperature.…”

“…[30] It is important to note, however, that these studies [27,30] were carried out on high purity zirconium, which has <50 ppm oxygen. [34] Soo [28] showed that the presence of oxygen in zirconium hardens prismatic slip and makes it significantly more temperature sensitive. Between 77 K and 473 K (À196°C and 200°C), Soo showed that prismatic slip in their lowest purity alloy (2000 ppm O) became easier by a factor 5.6 whereas the highest purity alloy (135 ppm O) became easier by a factor of 2.5.…”

On the mechanistic basis of deformation at the microscale in hexagonal close-packed metals

“…However, at higher interstitial contents, typical of commercial materials, this anomalous behaviour is supressed [50]. Thermal activation, particularly in relation to the Paton & Backofen [46] Levine [36] Levine [36] Akhtar [1] Akhtar [1] Akhtar [1] Akhtar & Teghtsoonian [4] Soo & Higgins [45] Sheely & Nash [48] [2,36,46,47], Zr [1,3,4,45] and Mg [48] single crystals with very low interstitial content.…”

Influence de l'hydrogène sur les mécanismes de déformation et d'endommagement des alliages de titane et de zirconium

“…exempt de cet élément. L'oxygène permet d'augmenter les caractéristiques mécaniques de manière particulièrement importante [6][7][8][9][10][11][12][13][14][15]. Notons que d'autres espèces telles que le carbone ou l'azote peuvent jouer des rôles voisins à celui de l'oxygène en terme de durcissement, ce qui a conduit rapidement à proposer la notion de teneur équivalente en oxygène : O eq (at%) = O + 2N + xC avec x = 0.5 pour le zirconium [7] et x = 0, 75 pour le titane [11].…”