Pure Single-Crystal Rutile Vanadium Dioxide Powders: Synthesis, Mechanism and Phase-Transformation Property

2008 ◽  
Vol 112 (48) ◽  
pp. 18810-18814 ◽  
Author(s):  
Chuanxiang Cao ◽  
Yanfeng Gao ◽  
Hongjie Luo
Keyword(s):  
Phase Transformation ◽  
Single Crystal ◽  
Vanadium Dioxide ◽  
Transformation Property ◽  
Synthesis Mechanism ◽  
Pure Single Crystal

Single Crystal Preparation of HP-(VO) 2 P 2 O 7 by Phase Transformation Under High Pressure

2002 ◽  
Vol 22 (3-4) ◽  
pp. 581-584 ◽  
Author(s):  
C. Gross ◽  
M. Anton ◽  
A. Löffert ◽  
A. Prokofiev ◽  
W. Assmus
Keyword(s):  
High Pressure ◽  
Phase Transformation ◽  
Single Crystal

Tribological behavior and phase transformation of single-crystal silicon in air

2008 ◽  
Vol 41 (3) ◽  
pp. 189-194 ◽  
Author(s):  
Xiaocheng Li ◽  
Jinjun Lu ◽  
Bin Liu ◽  
Shengrong Yang
Keyword(s):  
Phase Transformation ◽  
Single Crystal ◽  
Tribological Behavior ◽  
Single Crystal Silicon ◽  
Crystal Silicon

Irreversible single-crystal to polycrystal and reversible single-crystal to single-crystal phase transformations in cyanurates

2001 ◽  
Vol 57 (6) ◽  
pp. 791-799 ◽  
Author(s):  
Menahem Kaftory ◽  
Mark Botoshansky ◽  
Moshe Kapon ◽  
Vitaly Shteiman
Keyword(s):  
Phase Transformation ◽  
High Temperature ◽  
Low Temperature ◽  
Single Crystal ◽  
High Temperature Phase ◽  
Monoclinic Space Group ◽  
Temperature Phase ◽  
Space Group ◽  
Reversible Phase ◽  
Low Temperature Phase

4,6-Dimethoxy-3-methyldihydrotriazine-2-one (1) undergoes a single-crystal to single-crystal reversible phase transformation at 319 K. The low-temperature phase crystallizes in monoclinic space group P21/n with two crystallographically independent molecules in the asymmetric unit. The high-temperature phase is obtained by heating a single crystal of the low-temperature phase. This phase is orthorhombic, space group Pnma, with the molecules occupying a crystallographic mirror plane. The enthalpy of the transformation is 1.34 kJ mol−1. The small energy difference between the two phases and the minimal atomic movement facilitate the single-crystal to single-crystal reversible phase transformation with no destruction of the crystal lattice. On further heating, the high-temperature phase undergoes methyl rearrangement in the solid state. 2,4,6-Trimethoxy-1,3,5-triazine (3), on the other hand, undergoes an irreversible phase transformation from single-crystal to polycrystalline material at 340 K with an enthalpy of 3.9 kJ mol−1; upon further heating it melts and methyl rearrangement takes place.

Single Crystal Growth and its Microstructure in Co-Cr-Mo Alloys for Biomedical Applications

2012 ◽  
Vol 706-709 ◽  
pp. 561-565 ◽  
Author(s):  
Takayoshi Nakano ◽  
Keita Sasaki ◽  
Koji Hagihara ◽  
Takuya Ishimoto ◽  
Yusuke Fujii ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Crystal Growth ◽  
Single Crystal ◽  
Single Crystals ◽  
High Strength ◽  
Martensitic Phase ◽  
Surface Shape ◽  
Martensitic Phase Transformation ◽  
Ε Phase ◽  
Ar Gas

Co-Cr-Mo based alloys have been widely employed as heat resistant materials and as biomaterials for implants because of their high strength and superior wear resistance. In general, the alloys exhibit a very complicated composition-dependent microstructure containing stacking faults and related mechanical properties. Thus, the essential properties must be clarified by using not only polycrystals but also single crystals. To our knowledge, single crystals and related properties have not been reported elsewhere. Thus, Co-Cr-Mo single crystals were grown and used to analyze the microstructure and the related properties. Single crystals with a composition Co-27 mass% Cr-6 mass% Mo alloy defined by ASTM F75 were grown by two single crystal apparatuses: the optical floating zone and the Bridgman methods. The single crystals with the smooth-surface shape were successfully obtained in the Bridgman method under an Ar gas atmosphere at a crystal growth rate of 5.0 or 2.5 mm/h. A portion of the crystals contain Al as Al2O3 precipitates from the crucible. Since the Al2O3 precipitate induces martensitic phase transformation from fcc (γ) phase to hcp (ε) phase, the single crystals were separated into two parts (a) containing Al2O3 precipitate and (b) in the absence of the clear precipitate. The microstructure was significantly altered by the martensitic phase transformation from the γ to ε phase induced by stress field or heating. In addition, variant formation of ε phase has a large influence on the mechanical functions of these Co-Cr-Mo alloys. Novel findings were preliminary obtained in the single crystals.

Thermomechanical effects on phase transformations in single-crystal Cu–Al–Ni shape-memory alloy

2007 ◽  
Vol 22 (4) ◽  
pp. 994-1003 ◽  
Author(s):  
H.-S. Zhang ◽  
K. Komvopoulos
Keyword(s):  
Phase Transformation ◽  
Shape Memory Alloy ◽  
Single Crystal ◽  
Shape Memory ◽  
Elevated Temperatures ◽  
Czochralski Method ◽  
Tensile Tests ◽  
Transformation Temperatures ◽  
Experimental Findings ◽  
Cyclic Straining

Single-crystal rods of Cu–Al–Ni shape-memory alloy fabricated from a molten pool of 82 wt% Cu, 14 wt% Al, and 4 wt% Ni by the Czochralski method were first heated to ∼870 °C and then quenched to obtain austenitic microstructures. Various microanalysis techniques were used to determine the chemical composition, microstructure, and phase-transformation temperatures of the produced alloy. Cyclic tensile tests with in situ temperature control demonstrated the occurrence of pseudoelastic deformation at elevated and close to phase-transformation temperatures and provided insight into the temperature dependence of the phase-transformation stress, damping characteristics, and cyclic straining of single-crystal Cu–Al–Ni alloy. The stress hysteresis observed in the pseudoelastic deformation cycles decreased at elevated temperatures. The stress response at different temperatures is associated with the formation, growth, and coalescence of martensite variants. Stress-induced phase-transformation mechanisms, coalescence of twin variants, and energy dissipation by pseudoelastic deformation are discussed in the context of experimental findings. The results illustrate the potential of single-crystal Cu–Al–Ni as a structural material for dynamic microsystems and temperature sensors.

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