In-situ measurement of Ti-6Al-4V grain size distribution using laser-ultrasonic technique

2018 ◽  
Vol 154 ◽  
pp. 40-44 ◽  
Author(s):  
Feng Dong ◽  
Xiaochen Wang ◽  
Quan Yang ◽  
Huaqiang Liu ◽  
Dong Xu ◽  
...  
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
In Situ Measurement ◽  
Ultrasonic Technique ◽  
Laser Ultrasonic

scholarly journals Effect of Grain Size Distribution on Recrystallisation Kinetics in an Fe-30Ni Model Alloy

Metals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 369 ◽  
Author(s):  
Mo Ji ◽  
Claire Davis ◽  
Martin Strangwood
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Cold Deformation ◽  
Avrami Exponent ◽  
Model Alloy ◽  
Avrami Parameter ◽  
In Situ Heating

This paper discusses the role of grain size distribution on the recrystallisation rates and Avrami values for a Fe-30 wt. % Ni steel, which was used as a model alloy retaining an austenitic structure to room temperature. Cold deformation was used to provide uniform macroscopic strain distributions (strains of 0.2 and 0.3), followed by recrystallisation during annealing at 850–950 °C. It was shown that the Avrami parameter was directly related to the grain size distribution, with a lower Avrami exponent being seen for a larger average and wider grain size distribution. A method to predict the Avrami exponent from the grain size distribution was proposed. In situ heating in an SEM with EBSD showed the recrystallisation kinetics to be affected by differences in stored energy and nucleation in the different grain sizes supporting the proposed relationship.

scholarly journals Linking flow-stream variability to grain size distribution of suspended sediment from a satellite-based analysis of the Tiber River plume (Tyrrhenian Sea)

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
J. Pitarch ◽  
F. Falcini ◽  
W. Nardin ◽  
V. E. Brando ◽  
A. Di Cicco ◽  
...  
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Suspended Sediment ◽  
Grain Size Distribution ◽  
Flash Floods ◽  
Sandy Sediment ◽  
Tyrrhenian Sea ◽  
Tiber River ◽  
The Impact

AbstractSeveral coastal regions on Earth have been increasingly affected by intense, often catastrophic, flash floods that deliver significant amounts of sediment along shorelines. One of the critical questions related to the impact of these impulsive runoffs is “are flash floods more efficient in delivering non-cohesive sandy sediment along the coasts?” Here we relate flow stages (i.e., from erratic to persistent) to the grain size distribution of the suspended load, by performing a synergic analysis of in-situ river discharge and satellite-retrieved grain size distribution, from 2002 to 2014, covering the 2012 Tiber River (Italy) exceptional flood event. Our analysis shows novel and promising results regarding the capability of remote sensing in characterizing suspended sediment in terms of grain size distribution and reveals that erratic stages favour delivering of non-cohesive sandy sediment more than the persistent stages. This conclusion is supported by numerical simulations and is consistent with previous studies on suspended sediment rating curves.

scholarly journals Effect of grain size distribution on Raman analyses and the consequences for in situ planetary missions

2013 ◽  
Vol 44 (6) ◽  
pp. 916-925 ◽  
Author(s):  
F. Foucher ◽  
G. Lopez-Reyes ◽  
N. Bost ◽  
F. Rull-Perez ◽  
P. Rüßmann ◽  
...  
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Planetary Missions

Effects of processing conditions on solidification characteristics and mechanical properties of in situ magnesium metal matrix composites derived from polysilazane precursor

2019 ◽  
Vol 53 (26-27) ◽  
pp. 3741-3755 ◽  
Author(s):  
Nagaraj M Chelliah ◽  
Padaikathan Pambannan ◽  
MK Surappa
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Microstructural Evolution ◽  
Metal Matrix ◽  
Grain Morphology ◽  
Matrix Composites ◽  
Magnesium Metal

Polymer-derived in situ magnesium metal matrix composites (P-MMMCs) were fabricated by injecting a liquid or cross-linked polysilazane precursor into molten magnesium by a stir-casting method at two different melt temperatures of 700 and 800℃. Microstructural analysis reveals that the composites fabricated at 700℃ exhibit uni-modal grain size distribution having more or less columnar-shaped grain morphology. On the contrary, bi-modal grain size distribution with predominantly dendritic grain morphology occurs in the Mg matrix composites fabricated at 800℃. Such difference in grain morphology can be associated with variation in the availability of heterogeneous nucleation sites, and direction of heat flux during solidification. All of the fabricated composites were investigated for their solidification characteristics, microstructural evolution, micro/nano-hardness and compression properties. This article discusses the correlation between the processing parameters, microstructural evolution and mechanical properties of the as-cast in situ composites fabricated by liquid metallurgical route. Polymer-injection followed by in situ pyrolysis holds the potential of revolutionary processing technologies for producing castings of metal matrix nanocomposites, for example by bubbling the organic liquid with a carrier gas, e.g. nitrogen, into the molten metal by a Bessemer-like process.

In situ SEM analysis for deformation mechanism of micro/nanostructured 304 stainless steel with high strength and good plasticity

2018 ◽  
Vol 32 (17) ◽  
pp. 1850182 ◽  
Author(s):  
Jie Sheng ◽  
Peiqing La ◽  
Jiaqiang Su ◽  
Junqiang Ren ◽  
Jiqiang Ma ◽  
...  
Keyword(s):  
Grain Size ◽  
Stainless Steel ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Deformation Mechanism ◽  
Rolling Reduction ◽  
304 Stainless Steel ◽  
Bimodal Grain Size ◽  
Bimodal Grain Size Distribution

Bulk micro/nanostructured 304 austenitic stainless-steel plates with bimodal grain size distributions were prepared by Alumina Thermite Reaction at various temperatures and extents of rolling deformation. Rolling cogging of the sheet was performed with a rolling reduction of 40% at 1000[Formula: see text]C followed by rolling reduction of 80% at 700[Formula: see text]C. The strength and plasticity of the resulting micro/nanostructured 304 stainless steels with bimodal grain size distribution achieved the best matching, with tensile strength, yield strength, and elongation of 1410 MPa, 723 MPa and 15.3%, respectively. To better understand the deformation mechanism of this micro/nanostructured stainless steel sample, an in situ scanning electron microscopy technique was adopted. The crack initiation, propagation, and fracture were dynamically observed and recorded during the tensile deformation. Our results revealed that a stress concentration near the preset notch served as the initiation source and that microcracks were formed in the grain boundaries between micro- and nano-grains and then spread to the microcrystalline region until passing through the microcrystalline region or until passivation occurred in the microcrystalline region. The microcracks not only caused serious damage to the specimen but also generated back stress, which could lead to hardening of material, thereby enhancing the global ductility. Finally, the mechanism responsible for the enhanced plasticity and strength of the micro/nanostructured 304 stainless steel with a bimodal grain size distribution was analyzed and combined with the fracture morphology.

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