Crack growth in a nearly fully-lamellar gamma TiAl alloy at 650 °C and 800 °C under constant load conditions

In this paper, the operating principles of the acid battery and its features are discussed. The results of voltage tests containing the measurements conducted at the terminals of a loaded battery under constant load conditions, and dependent on time, are presented. The article depicts the principles of the development of electric models of acid batteries and their various descriptions. The principles for processing the results for the purpose of the determination and description of the battery model are characterized. The characteristics under stationary and non-stationary conditions are specified using glued functions and linear combinations of exponential functions, and the electrical parameters of the battery are determined as the components of the circuit, i.e., its electromotive force, resistance, and capacity. The dynamic characteristic of the battery in the form of transmittance was determined, using the Laplace transform. Possible uses of the crankshaft driving signals as diagnostic signals of the battery, electric starter, and internal combustion engine are also indicated.

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Ductile TiAl alloy with a Widmanstätten lamellar structure formed by rapid heating

Journal of Materials Research ◽

10.1557/jmr.2008.0138 ◽

2008 ◽

Vol 23 (4) ◽

pp. 949-953 ◽

Cited By ~ 5

Author(s):

J.P. Cui ◽

M.L. Sui ◽

Y.Y. Cui ◽

D.X. Li

Keyword(s):

Electric Current ◽

Lamellar Structure ◽

Tial Alloy ◽

Rapid Heating ◽

Pulse Treatment ◽

Electric Current Pulse ◽

Microstructural Refinement ◽

Tial Alloys ◽

Refinement Mechanism ◽

Fully Lamellar

Instead of conventional grain-refinement treatments for improving the ductility of fully lamellar TiAl alloys, multiorientational, lamellar, subcolony refinement with good ductility has been achieved simply by using an electric-current pulse treatment. The microstructural refinement mechanism is attributed to the transformation on heating of γ laths in the prior large-grain lamellar structure to Widmanstätten α in several orientations, which on subsequent cooling forms lamellar structure colonies in multiple orientations. This kind of refined multiple-colony lamellar structure was found to enhance the ductility of the TiAl alloy.

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Microstructure Transformation of a Refined High Nb Containing TiAl Alloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.747-748.38 ◽

2013 ◽

Vol 747-748 ◽

pp. 38-43 ◽

Cited By ~ 1

Author(s):

Li Hua Chai ◽

Liang Yang ◽

Jian Peng Zhang ◽

Zhi Yong Zhang ◽

Lai Qi Zhang ◽

...

Keyword(s):

Room Temperature ◽

Tial Alloy ◽

High Strength ◽

Temperature Limit ◽

Tial Alloys ◽

Β Phase ◽

Α Phase ◽

Refined Microstructure ◽

Fully Lamellar ◽

Sem Microstructure

High Nb containing TiAl alloys have been investigated traditionally as potential high temperature structural materials because of their high strength, good oxidation and creep resistance. However, the poor ductility and fracture toughness at room temperature limit their application, which could be improved by controlling microstructure to get refine and homogeneous fully lamellar structure. In this study, a high Nb containing TiAl alloy alloying Mn, B and Y with refined microstructure was produced. The solidification path was analyzed by DSC and SEM microstructure of the alloy was observed, after heating at a certain temperature for 1-24hrs and then quenching in water. The dissolution of β phase was also investigated. The results showed that the β phase could decompose only by heating in single β or near α phase field.

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BEHAVIOR OF PLASTIC DEFORMATION AND CRACK PROPAGATION ON FULLY LAMELLAR GAMMA-TiAl ALLOY

International Journal of Modern Physics B ◽

10.1142/s0217979210065921 ◽

2010 ◽

Vol 24 (15n16) ◽

pp. 2958-2963

Author(s):

MING SONG ◽

GUANGJIE MAO ◽

YUE MA ◽

SHENGKAI GONG

Keyword(s):

Plastic Deformation ◽

Plastic Zone ◽

Strain Field ◽

Tial Alloy ◽

Image Correlation ◽

Deformation Region ◽

Order Of Magnitude ◽

Plastic Deformation Region ◽

Fully Lamellar

Practical residual strain field around the microcrack tip of fully lamellar γ- TiAl alloy was estimate the by digital image correlation (DIC) technology with in-situ SEM observation. And the macro plastic deformation before fracture of such low ductility alloys was observed. The results showed that the size of plastic zone around microcrack tip was 2 ~ 10µ m which was much more smaller than the calculated value by fracture mechanics. During the magnified observation on the plastic deformation region, a series of microcracks were observed in the specimen without macro cracking. Furthermore, the size of distribution region of the microcracks were in the same order of magnitude with the calculated plastic zone near primary crack tip which just reflected the comprehensive effect of microcracks and the plastic deformation on the tips of them.

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Microstructures and Mechanical Properties of Ti-43Al-5V-4Nb-Y Alloy Consolidated by Spark Plasma Sintering

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.704.183 ◽

2016 ◽

Vol 704 ◽

pp. 183-189

Author(s):

Yong Jun Su ◽

Yi Feng Zheng ◽

De Liang Zhang ◽

Fan Tao Kong

Keyword(s):

Mechanical Properties ◽

Spark Plasma Sintering ◽

Tial Alloy ◽

Tensile Tests ◽

X Ray Diffraction ◽

X Ray ◽

Plasma Sintering ◽

Short Period ◽

Spark Plasma ◽

Fully Lamellar

TiAl alloy with a composition of Ti-43Al-5V-4Nb-Y (at.%) was prepared by spark plasma sintering (SPS). The TiAl powders were sintered between 650°C and 1300°C for 5 min under different loads. With the increasing of the temperature, the diffusion of the elements can be observed. Full compaction is achieved in a short period of time and the overall processing duration does not exceed 30 min. A fully lamellar structure was seen in the TiAl alloy after heat treatment. The microstructures of the samples were determined by X-ray diffraction and scanning electron microscopy. Their mechanical properties were evaluated by tensile tests performed at room temperature

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Crack Growth Rates of Alloy 600 From the Davis-Besse Reactor CRDM Nozzle #3 in PWR Environment

Volume 1: Codes and Standards ◽

10.1115/pvp2005-71504 ◽

2005 ◽

Author(s):

Omesh K. Chopra ◽

Bogdan Alexandreanu ◽

William J. Shack

Keyword(s):

Crack Growth ◽

Potential Drop ◽

Compact Tension ◽

Constant Load ◽

Alloy 600 ◽

Pressurized Water ◽

Control Rod ◽

Environmentally Assisted Cracking ◽

Water Reactors ◽

Nickel Base

Reactor–vessel internal components made of nickel–base alloys are susceptible to environmentally assisted cracking. A better understanding of the causes and mechanisms of this cracking may permit less conservative estimates of damage accumulation and requirements on inspection intervals of pressurized water reactors (PWRs). This paper presents crack growth rate (CGR) results for Alloy 600 removed from nozzle#3 of the Davis–Besse (D-B) control rod drive mechanism (CRDM). The tests were conducted on 1/4-T or 1/2-T compact tension specimens in simulated PWR environment, and crack extensions were determined by DC potential drop measurements. The experimental CGRs under cyclic and constant load are compared with the existing CGR data for Alloy 600 to determine the relative susceptibility of the D-B CRDM nozzle alloy to environmentally enhanced cracking. The CGRs under constant load for the nozzle material are higher than those predicted by the best-fit curve for Alloy 600 at 316 °C. The results also indicate significant enhancement of CGRs under cyclic loading in the PWR environment. Characterization of the material microstructure and tensile properties is described.

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