CrystaL Growth and Mechanical Properties of Semiconductor Alloys.

1988 ◽  
Author(s):  
D. A. Stevenson
Keyword(s):  
Mechanical Properties ◽  
Crystal Growth ◽  
Semiconductor Alloys

Functional analyses of chitinolytic enzymes in the formation of calcite prisms inPinctada fucata

2019 ◽  
Author(s):  
Hiroyuki Kintsu ◽  
Alberto Pérez-Huerta ◽  
Shigeru Ohtsuka ◽  
Taiga Okumura ◽  
Shinsuke Ifuku ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Crystal Growth ◽  
Calcium Carbonate ◽  
Small Angle ◽  
Organic Matrix ◽  
Pinctada Fucata ◽  
Prismatic Layer ◽  
Chitinolytic Enzymes ◽  
Organic Matrices

Abstract Background: The mollusk shells present distinctive microstructures that are formed by small amounts of organic matrices controlling the crystal growth of calcium carbonate. These microstructures show superior mechanical properties such as strength or flexibility. The shell of Pinctada fucata has the prismatic layer consisting of prisms of single calcite crystals. These crystals contain small-angle grain boundaries caused by a dense intracrystalline organic matrix network to improve mechanical strength. Previously, we identified chitin and chitinolytic enzymes as components of this intracrystalline organic matrix. In this study, we analyzed the function of those organic matrices in calcium carbonate crystallization by in vitro and in vivo experiments.Results: We analyzed calcites synthesized in chitin gel with or without chitinolytic enzymes by using transmission electron microscope (TEM) and atom probe tomography (APT). TEM observations showed that grain boundary was more induced as concentration of chitinolytic enzymes increased and thus, chitin became thinner. In an optimal concentration of chitinolytic enzymes, small-angle grain boundaries were observed. APT analysis showed that ion clusters derived from chitin were detected. In order to clarify the importance of chitinolytic enzymes on the formation of the prismatic layer in vivo , we performed the experiment in which chitinase inhibitor was injected into a living Pinctada fucata and then analyzed the change of mechanical properties of the prismatic layer. The hardness and elastic modulus increased after injection of chitinase inhibitor. Electron back scattered diffraction (EBSD) mapping data showed that the spread of crystal orientations in whole single crystal also increased by the effect of inhibitor injections.Conclusion: Our results suggested that chitinolytic enzymes may function cooperatively with chitin to regulate the crystal growth and mechanical properties of the prismatic layer, and chitinolytic enzymes are essential for the formation of the normal prismatic layer of P. fucata.

Microstructure and Mechanical Properties of Ti-6Al-4V Alloy Samples Fabricated by Selective Laser Melting

2018 ◽  
Vol 770 ◽  
pp. 179-186 ◽  
Author(s):  
Jing Bo Gao ◽  
Xiao Li Zhao ◽  
Ju Kun Yue ◽  
Meng Chao Qi ◽  
De Liang Zhang
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Crystal Growth ◽  
Yield Strength ◽  
Selective Laser Melting ◽  
Lamellar Structure ◽  
Growth Direction ◽  
Laser Melting ◽  
Α Phase ◽  
Dog Bone

Ti-6Al-4V (wt%) alloy samples with dog-bone and box shapes respectively were fabricated by selective laser melting (SLM). The microstructures and mechanical properties of the 3D printed Ti-6Al-4V samples with and without heat treatment were characterized and tested. The microstructures of the as-fabricated dog-bone shaped samples were mainly composed of acicular α’ phase. After annealing at 700°C, the acicular α’ phase changed into an α/β lamellar structure. After solution treatment at 955°C, water quenching and aging at 550°C, the microstructure was mainly composed of primary α phase and α/β lamellar structure. The optimum heat treatment is annealing, and the mechanical properties of the annealed sample are as follows: yield strength: 1015 MPa, ultimate tensile strength (UTS): 1083 MPa and elongation to fracture: 7.9%. The microstructures of the box-shaped samples after annealing mainly consist of α phase and α/β lamellar structure. When stretched along the direction parallel to the crystal growth direction, the yield strength and UTS of the sample are 1054 and 1090 MPa，and its elongation to fracture is 6.3%. When stretched along the direction perpendicular to the crystal growth direction, the yield strength and UTS of the sample are 1019 and 1068 MPa respectively, and its elongation to fracture is 8.7%.

scholarly journals Crystal Dislocations: Their Impact on Physical Properties of Crystals

Crystals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 413
Author(s):  
Peter Lagerlof
Keyword(s):  
Crystal Structure ◽  
Mechanical Properties ◽  
Crystal Growth ◽  
Physical Properties ◽  
Phase Transformations ◽  
Electronic Properties ◽  
Martensitic Phase ◽  
Martensitic Phase Transformations

It is rare to find technical applications involving a material of any crystal structure that is not impacted by dislocations—which affect the material’s mechanical properties, interfaces, martensitic phase transformations, crystal growth, and electronic properties, to name a few. [...]

Comparison of Apatite Formation on Polyamide Films Containing Carboxyl and Sulfonic Groups in a Solution Mimicking Body Fluid

2006 ◽  
Vol 309-311 ◽  
pp. 477-480
Author(s):  
Chikara Ohtsuki ◽  
Takahiro Kawai ◽  
Masanobu Kamitakahara ◽  
Masao Tanihara ◽  
Toshiki Miyazaki ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Crystal Growth ◽  
Simulated Body Fluid ◽  
Calcium Ions ◽  
Body Fluid ◽  
Functional Group ◽  
Carboxyl Groups ◽  
Apatite Formation ◽  
Ion Concentrations ◽  
Polyamide Film

Apatite formation on polyamide films containing either carboxyl or sulfonic groups was compared in 1.5SBF, whose ion concentrations are 1.5 times those of a simulated body fluid (SBF). The sulfonic groups induced the apatite nucleation earlier than the carboxyl groups. In contrast, the rate of crystal growth depended not on the kind of functional group, but on the degree of supersaturation of the surrounding solution. The more ready association of sulfonic groups with calcium ions may lead to earlier apatite nucleation than that of carboxyl groups. Adhesive strength of the apatite layer to polyamide film containing sulfonic groups was significantly lower than that with carboxyl groups depending on the chemical interactions as well as on the mechanical properties of the polyamide film.

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