An Exceptionally Stable and Scalable Sugar–Polyolefin Frank–Kasper A15 Phase

2019 ◽  
Vol 132 (4) ◽  
pp. 1537-1542 ◽  
Author(s):  
Kätchen K. Lachmayr ◽  
Charlotte M. Wentz ◽  
Lawrence R. Sita
Keyword(s):  
A15 Phase

Microstructure of Nb3 (AlSiB) superconducting tapes with extremely high critical current densities

1989 ◽  
Vol 4 (3) ◽  
pp. 526-529 ◽  
Author(s):  
Mireille Treuil Clapp ◽  
Zhang Jian ◽  
Tariq Manzur
Keyword(s):  
Critical Current ◽  
Melt Spinning ◽  
Quenching Rate ◽  
Fine Grained ◽  
Annealing Conditions ◽  
Second Phases ◽  
Current Densities ◽  
Rapidly Solidified ◽  
Equiaxed Grains ◽  
A15 Phase

Alloys of Nb73Al12Si14.5B0.5 were rapidly solidified into amorphous ribbons using the melt spinning technique. These were isothermally annealed at temperatures ranging from 660 to 780 °C. The A15 phase began to crystallize at 700 °C and small amounts of second phases appeared at the higher temperatures. Crystallization was dependent on quenching rate as well as annealing conditions. Below 750 °C nucleation was nonuniform and was enhanced by surfaces and quenched-in nuclei. Above 750 °C nucleation became more uniform and completely crystalline ribbons with equiaxed grains ∼30 nm in diameter were obtained. These ultra fine grained ribbons had extremely high superconducting critical current densities of 8 × 1010 A/m2 and 5 × 1010 A/m2 at magnetic fields of 0.5 and 15 tesla, respectively, at 4.2 K.

The Mechanical Behavior and Deformation Mechanisms of Nb-Al-V Alloys

1996 ◽  
Vol 460 ◽  
Author(s):  
D. K. Tappin ◽  
D. N. Horspool ◽  
L. S. Smith ◽  
M. Aindow
Keyword(s):  
Mechanical Behavior ◽  
Room Temperature ◽  
Compression Testing ◽  
Deformation Mechanisms ◽  
Dislocation Activity ◽  
Partial Dislocations ◽  
Shear Transformation ◽  
B2 Phase ◽  
A15 Phase ◽  
Phase Strains

ABSTRACTA series of Nb-Al-V alloys containing 20–40 at. % V and 10–25 at. % Al have been investigated. The phase distributions in the alloys indicate that Al promotes the formation of the A15 phase whilst V stabilises a B2 phase. Room temperature compression testing revealed that the B2 is inherently ductile such that for the alloys with less than 40% by volume of the A15 phase, strains of over 50% were obtained easily. The 2% offset yield stresses of these alloys did not vary significantly with composition, being 1.2±0.1GPa in each case. TEM studies were used to show that the deformation in the B2 phase occurs predominantly by the glide of screw-type super-partial dislocations with b=l/2<111> on {110} and {112}. In some alloys this dislocation activity was preceded by the formation of pseudo-twins, via a martensitic shear transformation.

Metastable A15 phase Nb3Si synthesized by high dynamic pressure

1989 ◽  
Vol 1 (4) ◽  
pp. 267-289 ◽  
Author(s):  
J. J. Neumeier ◽  
W. J. Nellis ◽  
M. B. Maple ◽  
M. S. Torikachvili ◽  
K. N. Yang ◽  
...  
Keyword(s):  
Dynamic Pressure ◽  
High Dynamic Pressure ◽  
High Dynamic ◽  
A15 Phase

Investigation of B2 and Related Phases in Ti-Modified Nb-Al Alloys

1993 ◽  
Vol 322 ◽  
Author(s):  
D.-H. Hou ◽  
S.S. Yang ◽  
J. Shyue ◽  
H.L. Fraser
Keyword(s):  
Site Occupancy ◽  
Orthorhombic Phase ◽  
Intermetallic Alloys ◽  
Heat Treated ◽  
Three Phase ◽  
Ordered Intermetallic ◽  
Tie Lines ◽  
Second Phases ◽  
A15 Phase ◽  
O Phase

AbstractThe B2 ordering and phase stability of three ordered intermetallic alloys with compositions (in at.%) of Nb-15Al-10Ti (10Ti alloy), Nb-15A1-40Ti (40Ti alloy), and Nb-15Al-25Ti (25Ti alloy) have been studied. All three alloys have the B2 crystal structure in the as-cast form. The Atom Location by Channeling Enhanced Microanalysis (ALCHEMI) technique has been employed to assess the site occupancy of these B2 alloys. The results of site occupancy are represented as Ordering Tie Lines on a ternary composition diagram. Various second phases were observed in heat treated samples. An ω-type phase was found in the 1OTi alloy in samples heat treated for 10 minutes and 4 hours at 900°C. At 800°C, orthorhombic phase was found in the 40Ti alloy while a three phase microstructure of o-phase/B2/A15 was observed in both the 10Ti and 25Ti alloys. Annealing at 1100°C leads to the dissolution of the o-phase and the presence of A15 phase in the 10Ti and 25Ti alloys, but no other phase in the 40Ti alloy. The observed phase equilibria in these alloys are compared with those in the literature.

Ternary A15-phase regions in the Nb-Sn-Si and Nb-Sn-As systems

1977 ◽  
Vol 52 (2) ◽  
pp. 271-277 ◽  
Author(s):  
R.M. Waterstrat ◽  
J. Müller
Keyword(s):  
A15 Phase

Powder metallurgical synthesis of the superconducting niobium-aluminium-germanium A15 phase

1975 ◽  
Vol 42 (3) ◽  
pp. 335-344 ◽  
Author(s):  
J.A. Cave ◽  
T.J. Davies ◽  
F.C. Carpenter
Keyword(s):  
A15 Phase

Microstructure & Phase Transformation in Rapidly Solidified V-Ga Alloys

1986 ◽  
Vol 80 ◽  
Author(s):  
M. W. Park ◽  
S. H. Whang ◽  
S. Karmarkar ◽  
D. Divecha
Keyword(s):  
Heat Treatment ◽  
Phase Transformation ◽  
Grain Refinement ◽  
Rapid Solidification ◽  
Rapid Quenching ◽  
X Ray Diffraction ◽  
X Ray ◽  
Rapidly Solidified ◽  
A15 Phase

AbstractThe A15 Phase forming V-Ga alloys were processed into ribbons and foils by rapid solidification techniques. Microstructures and phase transformation in these alloys by rapid solidification and succeeding heat treatment were investigated by x-ray diffraction and TEM. It is shown that equilibrium A15 phases can readily be suppressed by rapid quenching in these alloys. A significant grain refinement resulting from the rapid solidification also was observed. Microhardnesses of these alloys as a function of Ga concentration were determined.

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