DEFORMATION OF Al2O3 SINGLE CRYSTALS BETWEEN 25°C AND 1800°C : BASAL AND PRISMATIC SLIP

1981 ◽  
Vol 42 (C3) ◽  
pp. C3-43-C3-47 ◽  
Author(s):  
J. Castaing ◽  
J. Cadoz ◽  
S. H. Kirby
Keyword(s):  
Single Crystals ◽  
Prismatic Slip

Crack Orientation Dependence for Fatigue Behavior of Titanium Single Crystals

2007 ◽  
Vol 345-346 ◽  
pp. 351-354 ◽  
Author(s):  
Takahiro Sakamoto ◽  
Shinji Ando ◽  
Hiromoto Kitahara ◽  
Masayuki Tsushida ◽  
Hideki Tonda
Keyword(s):  
Single Crystals ◽  
Fatigue Behavior ◽  
Thin Sheet ◽  
Orientation Dependence ◽  
Test Method ◽  
Prismatic Slip ◽  
Bending Mode ◽  
Bending Fatigue Test ◽  
Fixed End ◽  
Fatigue Fracture Behavior

In this present study, the fatigue behavior of titanium single crystals containing cracks growing in different crystallographic orientations has been investigated. To investigate fatigue fracture behavior of small single crystals, plain bending fatigue test method for thin sheet specimen was developed. One end of the sheet specimen is fixed at a voice coil of the loudspeaker and the other end is set free. A bending mode resonance occurs in the specimen due to forced vibration at the fixed end. In A-specimen, the notch plane and the direction are (11-20) and [1-100], respectively, the crack propagated parallel to {1-100} plane and striation-like markings were observed on the fatigue surfaces. In B-specimen with a notch of (1-100) and [11-20], the crack also propagated parallel to {1-100} plane as similar to A-specimen. These cracks are deduced to extend by alternating shear on two intersecting prismatic slip systems at the crack tip. In F-specimen with a notch of (0001) and [11-20], the crack propagated parallel to (0001) and twins were observed near the crack. As a result, S-N curves of each specimen showed strong orientation dependence and the fatigue strength of F-specimen was the highest in these specimens.

Activities of Non-Basal Slips in Deformation of Magnesium Alloy Single and Poly Crystals

2018 ◽  
Vol 941 ◽  
pp. 1242-1247
Author(s):  
Shinji Ando ◽  
Hiroaki Rikihisa ◽  
Masayuki Tsushida ◽  
Hiromoto Kitahara
Keyword(s):  
Magnesium Alloy ◽  
Single Crystals ◽  
Basal Plane ◽  
Basal Slip ◽  
Tensile Deformation ◽  
Deformation Behaviour ◽  
Pure Magnesium ◽  
Prismatic Slip ◽  
Polycrystalline Specimen ◽  
Yttrium Addition

In this study, to investigate effects of yttrium and other elements for non-basal slips, magnesium alloy single crystals were stretched parallel to basal plane in various temperatures, and polycrystalline magnesium alloys were also tested to estimate contribution of non-basal slips to their tensile deformation behaviour. In pure magnesium single crystals, second order pyramidal (c+a) slip (SPCS) was observed at 298K. Above room temperature, first order pyramidal (c+a) slip (FPCS) was active. In the Mg - (0.6-0.9) Y alloy single crystals, FPCS was observed at 77K to 298K, while yield stress of the Mg-Y alloy single crystals was higher than that of pure magnesium. In tensile test of polycrystalline specimen, slips lines of non-basal slip systems such as SPCS, FPCS and prismatic slip were observed even at yielding in addition to basal slip lines. Among the non-basal slips, activities of FPCS and prismatic slips were increased with increasing strain in Mg - Y alloy polycrystals. Our study suggested that active non-basal slip system in tension parallel to basal plane is (c+a) pyramidal slip and enhanced ductility of magnesium - yttrium alloy would be caused from increased activity of FPCS by yttrium addition.

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