Enhanced combination of strength and ductility in the semi-solid rheocast hypereutectic Al Si alloy with the effect of in-situ TiB2 particles

Abstract. Atmospheric soluble organic aerosol material can become solid or semi-solid. Due to increasing viscosity and decreasing diffusivity, this can impact important processes such as gas uptake and reactivity within aerosols containing such substances. This work explores the dependence of shikimic acid ozonolysis on humidity and thereby viscosity. Shikimic acid, a proxy for oxygenated reactive organic material, reacts with O3 in a Criegee-type reaction. We used an environmental microreactor embedded in a scanning transmission X-ray microscope (STXM) to probe this oxidation process. This technique facilitates in situ measurements with single micron-sized particles and allows to obtain near-edge X-ray absorption fine structure (NEXAFS) spectra with high spatial resolution. Thus, the chemical evolution of the interior of the particles can be followed under reaction conditions. The experiments show that the overall degradation rate of shikimic acid is depending on the relative humidity in a way that is controlled by the decreasing diffusivity of ozone with decreasing humidity. This decreasing diffusivity is most likely linked to the increasing viscosity of the shikimic acid–water mixture. The degradation rate was also depending on particle size, most congruent with a reacto-diffusion limited kinetic case where the reaction progresses only in a shallow layer within the bulk. No gradient in the shikimic acid concentration was observed within the bulk material at any humidity indicating that the diffusivity of shikimic acid is still high enough to allow its equilibration throughout the particles on the timescale of hours at higher humidity and that the thickness of the oxidized layer under dry conditions, where the particles are solid, is beyond the resolution of STXM.

Download Full-text

In situ study of granular micromechanics in semi-solid carbon steels

Acta Materialia ◽

10.1016/j.actamat.2013.03.043 ◽

2013 ◽

Vol 61 (11) ◽

pp. 4169-4179 ◽

Cited By ~ 30

Author(s):

J. Fonseca ◽

C. O’Sullivan ◽

T. Nagira ◽

H. Yasuda ◽

C.M. Gourlay

Keyword(s):

Carbon Steels ◽

Solid Carbon ◽

In Situ Study ◽

Granular Micromechanics ◽

Semi Solid

Download Full-text

Investigation of in situ synthesized TiB2 particles in iron-based composite coatings processed by hybrid submerged arc welding

Materials Testing ◽

10.1515/mt-2020-0104 ◽

2021 ◽

Vol 63 (7) ◽

pp. 630-638

Author(s):

Mustafa Kaptanoglu ◽

Mehmet Eroglu

Keyword(s):

Arc Welding ◽

Composite Coatings ◽

Tib2 Particle ◽

Submerged Arc Welding ◽

Wear Properties ◽

Gas Atmosphere ◽

Iron Based ◽

Tib2 Particles ◽

Submerged Arc

Abstract In the study for this contribution, production of in situ synthesized TiB2 particles in iron-based composite coatings using four different submerged arc welding powders (fluxes) containing increasing amounts of ferrotitanium and ferroboron with S1 welding wire, were targeted. For this purpose, coating deposition was carried out to improve the hardness and wear properties of the AISI 1020 steel surfaces using hybrid submerged arc welding. In hybrid submerged arc welding, the welding pool is protected by both welding powders and an argon gas atmosphere. To examine the composite coatings, visual, chemical, microstructural analyses and hardness and wear tests were carried out. With the use of increasing amounts of ferrotitanium and ferroboron in the welding powders, it was observed that the microstructure of the coatings changed in terms of TiB2 particle geometries such as rectangular and hexagonal; volume fractions of TiB2 particles in the coating microstructures increased; hardness values of coatings were enhanced from 34 HRC to 41 HRC; the wear resistance of the coatings improved, and worn surface images of the coatings caused by the counter body changed from continuous with deep scratches to discontinuous with fine scratches and crater cavities.

Download Full-text

Study of Microstructure Evolution during Semi-Solid Processing of an In-Situ Al Alloy Composite

Materials and Manufacturing Processes ◽

10.1080/10426914.2014.952040 ◽

2015 ◽

Vol 30 (3) ◽

pp. 356-366 ◽

Cited By ~ 9

Author(s):

Santosh Kumar ◽

Prosenjit Das ◽

Sandeep K. Tiwari ◽

Manas K. Mondal ◽

Supriya Bera ◽

...

Keyword(s):

Microstructure Evolution ◽

Al Alloy ◽

Alloy Composite ◽

Semi Solid

Download Full-text

Mechanical And Superconducting Properties Of Cu-Nb3Sn In Situ Produced Composite Wires

MRS Proceedings ◽

10.1557/proc-12-277 ◽

1981 ◽

Vol 12 ◽

Author(s):

A. Kolb-Telieps ◽

B.L. Mordike ◽

M. Mrowiec

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Yield Strength ◽

Wide Temperature Range ◽

Volume Fraction ◽

Superconducting Properties ◽

Temperature Range ◽

Composite Wires ◽

Strength And Ductility

ABSTRACTCu-Nb composite wires were produced from powder, electrolytically coated with tin and annealed to convert the Nb fibres to Nb 3Sn. The content was varied between 10 wt % and 40 wt %. The superconducting properties of the wires were determined. The mechanical properties, tensile strength, yield strength and ductility were measured as a function of volume fraction and deformation over a wide temperature range. The results are compared with those for wires produced by different techniques.

Download Full-text

Characterization of Shear Deformation Based on In-situ Observation of Deformation in Semi-Solid Al-Cu Alloys and Water-Particle Mixture

Tetsu-to-Hagane ◽

10.2355/tetsutohagane.99.141 ◽

2013 ◽

Vol 99 (2) ◽

pp. 141-148 ◽

Cited By ~ 2

Author(s):

Tomoya Nagira ◽

Hiroyoshi Yokota ◽

Shugo Morita ◽

Hideyuki Yasuda ◽

Masato Yoshiya ◽

...

Keyword(s):

Shear Deformation ◽

In Situ Observation ◽

Water Particle ◽

Particle Mixture ◽

Cu Alloys ◽

Semi Solid

Download Full-text

Study on Rheo-Diecasting for In Situ Synthesized Mg2Si/AM60 Composites

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.383-390.707 ◽

2011 ◽

Vol 383-390 ◽

pp. 707-711

Author(s):

Hong Yan ◽

Yong Hu ◽

Xiao Quan Wu

Keyword(s):

Die Casting ◽

Casting Machine ◽

Chinese Script ◽

Matrix Composites ◽

Forming Process ◽

Magnesium Matrix ◽

Magnesium Matrix Composites ◽

Mechanical Stirring ◽

Semi Solid

Magnesium alloys have high specific strength, specific stiffness, excellent thermal conductivity and casting properties, which have a great prospects development in the industry, However, its low plasticity and ductility limited its application. Magnesium matrix composites can effectively improve its performance. Magnesium alloy die-casting is the main forming process, the conventional high-pressure die-casting (HPDC) defects in multi-cavity type, easy to volume gas, non-heat-treated. Compared with HPDC, the rheo-diecasting (RDC) process has been greatly developed for near-net shape components. In this paper, Mg2Si /AM60 composites is fabricated by in-situ synthesis and semi-solid magnesium matrix composites which are rheoformed in the die-casting machine are prepared by mechanical stirring. The results indicate that the microstructure of composites is non-dendritic and Chinese script type Mg2Si are fine distributed. The fundamental morphology of microstructure by HPDC is dendrite and liquid-phase distributed between dendrite irregularly. The RDC samples have close-to-zero porosity, less segregation, the most of semi-solid of microstructure in rheo-diecasting is spherical or as-spherical structure.

Download Full-text