Magnetic and Mechanical Properties of Directionally Solidified Fe-6.5wt.%Si Alloy

Directional solidification technique was employed to produce Fe-6.5wt.%Si alloy with coarse columnar-grain structure, which was almost single crystal. The sectional diameters of columnar grains range from 2.2 to 6.8 mm. The saturation magnetic induction was 2.39 T. In this work, grain growth started from either a Fe-6.5wt.%Si crystal which was not melted at bottom of the specimen or a freely nucleated Fe-6.5wt.%Si crystal as the specimen was completely melted. It was found that the starting situation of the directional solidification plays an important role in the crystal orientation, and hence in properties.

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The Mechanical and Deformation Behavior of TWIP Steel Prepared by Directional Solidification

Materials Science Forum ◽

10.4028/www.scientific.net/msf.783-786.761 ◽

2014 ◽

Vol 783-786 ◽

pp. 761-765 ◽

Cited By ~ 2

Author(s):

Dan Wang ◽

Kun Wang ◽

Zi Mu Shi ◽

Fu Sheng Han

Keyword(s):

Mechanical Properties ◽

Strain Hardening ◽

Twip Steel ◽

True Strain ◽

Longitudinal Direction ◽

True Stress ◽

Grain Structure ◽

Directionally Solidified ◽

Twip Steels ◽

Columnar Grain

A directionally solidified TWIP steel (Fe-25Mn-2.5Al-2.5Si) was prepared by liquid metal cooling technology. The microstructure and mechanical behavior were examined and compared with usually solidified samples. The directionally solidified TWIP steel shows a typical columnar grain structure, and the maximum true stress and true strain along the longitudinal direction of the sample are 1060MPa and 71% respectively. As a comparison, the usually solidified samples shows an equiaxed grain microstructure with the maximum true stress and true strain of only 994MPa and 58%, respectively. Moreover, the two solidification modes also lead to very different strain hardening behavior, particularly in the changes of strain hardening rate with strain. This suggests that the grain boundary plays a key role in the mechanical properties of TWIP steels, and changing the grain boundaries can be effective to improve the comprehensive mechanical properties of TWIP steels.

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Microstructure and Mechanical Properties of a Rapid Directionally Solidified Ti47Al Alloy

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.117-119.217 ◽

2011 ◽

Vol 117-119 ◽

pp. 217-221

Author(s):

Rui Run Chen ◽

Hong Sheng Ding ◽

Jing Jie Guo ◽

Yan Qing Su ◽

Heng Zhi Fu

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Grain Growth ◽

Axial Direction ◽

Longitudinal Section ◽

Growth Direction ◽

Directionally Solidified ◽

Compressive Properties ◽

Dendritic Core ◽

Columnar Grains

The ingot of Ti47Al alloy was prepared by a newly developed rapid directional solidification, the microstructure and compressive properties of the ingot was observed and tested. The results show that the macrostructure consisted mainly of coarse columnar grains parallel to the axial direction, with the size of 0.5mm wide and 10mm in length. The direction of lamellar is almost perpendicular to the growth direction in the longitudinal section and no dendritic core is found. The average ultimate compressive strength of the specimens with grain growth parallel/perpendicular to the compressive direction is 1233.3 and 861.7 MPa respectively. The fracture mode for specimens with grain growth parallel to the compressive direction exhibits predominantly translamellar fracture, however, that for specimens with grain growth perpendicular to the compressive direction exhibits predominantly delamenation or interlamellar fracture.

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Evolution of Microstructure and Microsegregation of Ti-45Al-8Nb Alloy during Directional Solidification

Advances in Materials Science and Engineering ◽

10.1155/2018/1713835 ◽

2018 ◽

Vol 2018 ◽

pp. 1-9

Author(s):

Xiangjun Xu ◽

Rui Hu ◽

Junpin Lin ◽

Jian Guo

Keyword(s):

Mushy Zone ◽

Solidification Rate ◽

Solidus Temperature ◽

Melting Zone ◽

Optical Microscope ◽

Directionally Solidified ◽

Good Oxidation Resistance ◽

Columnar Grains ◽

Columnar Grain ◽

Evolution Of Microstructure

High Nb-containing TiAl alloys have good oxidation resistance and mechanical properties, but the microstructure and the properties are substantially affected by the segregation. To quantitatively investigate the segregation behavior of Al during solidification, microstructures of directionally solidified (DS) Ti-45Al-8Nb (in atomic percent) alloy prepared at withdrawing rates of 30 μm/s and 200 μm/s and a temperature gradient of 4200 K/m were observed by optical microscope and electronic probe microanalyzer. The microsegregations were characterized by wave dispersive spectroscopy. The results show that the DS ingots include the no melting zone, directionally solidified zone with columnar grains, mushy zone, and quenched liquid zone. The primary dendritic arm spacings are 353 μm and 144 μm, respectively, for the two ingots. But the solidified microstructures of the ingots are large lamellar colonies, which contain a few B2 patches and γ bands induced by microsegregation. From dendritic zone to columnar zone, the volume fractions of B2 patches and γ bands decrease. The segregation extents of Al and Nb decrease with the increase of solidification rate. There exists an obvious back diffusion process of Al during solidification and cooling after solidification. According to evolution of Al concentration profiles from mushy zone to columnar grain zone, interdiffusion coefficient for Al in β-Ti at near solidus temperature is semiquantitatively calculated, and the value is (6 – 11) × 10−11 m2/s.

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Comparison of Experimental and Computational Aspects of Grain Growth in Al-Foil

MRS Proceedings ◽

10.1557/proc-652-y1.8 ◽

2000 ◽

Vol 652 ◽

Author(s):

Melik C. Demirel ◽

Andrew P. Kuprat ◽

Denise C. George ◽

Bassem S. El-Dasher ◽

Neil N. Carlson ◽

...

Keyword(s):

Grain Boundary ◽

Grain Growth ◽

Three Dimensional ◽

Interface Energy ◽

Grain Structure ◽

Electron Backscattered Diffraction ◽

Boundary Properties ◽

Ebsd Technique ◽

Columnar Grain ◽

Grain Boundary Motion

ABSTRACTGrain boundary and crystallographic orientation information of an Al-foil with a columnar grain structure is characterized by Electron Backscattered Diffraction (EBSD) technique. The starting microstructure and grain boundary properties are implemented as an input for the three- dimensional grain growth simulation. In the computational model, minimization of the interface energy is the driving force for the grain boundary motion. The computed evolved microstructure is compared with the final experimental microstructure, after annealing at 550 °C. Good agreement is observed between the experimentally obtained microstructure and the simulated microstructure. The constitutive description of the grain boundary properties was based on a 1- parameter characterization of the variation in mobility with misorientation angle.

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The effect of substrate bias on the characteristics of CrN coatings deposited by DC-superimposed HiPIMS system

International Journal of Modern Physics B ◽

10.1142/s0217979217440325 ◽

2017 ◽

Vol 31 (16-19) ◽

pp. 1744032 ◽

Cited By ~ 3

Author(s):

X. Zuo ◽

F. Xia ◽

D. Zhang ◽

P. L. Ke ◽

Q. M. Wang ◽

...

Keyword(s):

Mechanical Properties ◽

Bias Voltage ◽

Indentation Test ◽

Grain Structure ◽

Substrate Bias ◽

Cross Sectional ◽

Microstructure And Mechanical Properties ◽

Columnar Grain ◽

Influence Of Substrate ◽

Crn Coatings

Chromium nitride coatings were prepared by reactive DC-superimposed high-power-impulse magnetron sputtering (HiPIMS) system. The influence of substrate bias on the microstructure and mechanical properties of CrN coatings was investigated. XRD and cross-sectional SEM were utilized to characterize the film structures. Mechanical properties were characterized by nanoindentation and Vickers indentation test. The results revealed that the microstructure and mechanical properties of CrN coatings were affected by bias voltage. The CrN coatings exhibited dense and fine columnar grain structure with the hardness of about 18.7 GPa. The fracture toughness of CrN coatings was around 3.16 MPa ⋅ m[Formula: see text]. However, further increase of the bias voltage from −250 V to −300 V led to the degradation of coating properties.

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Failure Mechanisms in Directionally Solidified Alumina-Titania Composites

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.290.199 ◽

2005 ◽

Vol 290 ◽

pp. 199-202 ◽

Cited By ~ 7

Author(s):

Carmen Baudín ◽

Ali Sayir ◽

Marie Helene Berger

Keyword(s):

Mechanical Properties ◽

Directional Solidification ◽

Mechanical Behaviour ◽

Failure Mechanisms ◽

Secondary Phase ◽

Al2o3 Content ◽

Directionally Solidified ◽

Two Phase ◽

Load Bearing

The mechanical properties of directionally solidified two-phase eutectics can be superior to that of either constituent alone due to the strong constraining effects of the interlocking microstructure. The present work focuses on the failure mechanisms that occur in Al2O3-Al2TiO5 composites fabricated by directional solidification. Two compositions rich in alumina have been considered. The constituents were the same in both materials, primary Al2O3 dendrites surrounded by a TiO2-containing phase, with different morphological and size characteristics. The dendrites in the material containing the smallest amount of Al2O3 were short and highly interpenetrated by the secondary phase whereas those of the material with the highest Al2O3 content were long and much less interpenetrated. The mechanical behaviour in bending was determined by these microstructural differences because the load bearing phase in these directionally solidified materials in the system Al2O3-Al2TiO5 are the Al2O3 dendrites.

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Deformation of Diffusion-Bonded Bi-Pst and Directionally Solidified Crystals of TiAl

MRS Proceedings ◽

10.1557/proc-460-53 ◽

1996 ◽

Vol 460 ◽

Cited By ~ 1

Author(s):

K. Kishida ◽

D. R. Johnson ◽

Y. Shimada ◽

Y. Masuda ◽

H. Inui ◽

...

Keyword(s):

Directional Solidification ◽

Diffusion Bonding ◽

Flow Behavior ◽

Lamellar Microstructure ◽

Growth Direction ◽

Current Status ◽

Directionally Solidified ◽

Lamellar Orientation ◽

Columnar Grain ◽

And Diffusion

ABSTRACTWith a data base now available on the microstructural characteristics and the deformation, fracture and macroscopic flow behavior of polysynthetically twinned (PST) crystals of γ/α2 TiAl-base alloys, an approach to achieve a good combination of strength, ductility and toughness in γ/α2 TiAl-base alloys was proposed using directional solidification (DS) techniques to produce a columnar grain material with the lamellar orientation aligned parallel to the growth direction. Such alignment of the lamellar microstructure was recently accomplished in γ/α2 TiAl-base alloys of near equiatomic compositions using an appropriately oriented seed crystal from the Ti-Al-Si system.At the same time, bi-PST crystals, each containing a planar boundary parallel to the loading axis were prepared by directional solidification and diffusion bonding of two PST crystals. Such bi-PST crystals were deformed in tension at room temperature and their deformation behavior was examined in terms of the compatibility requirements imposed at the grain boundary and the interaction of the two component PST crystals.In this paper, (i) the current status of our DS processing efforts, (ii) some results of microscopic characterization of grain boundaries in diffusion bonded bi-PST crystals and (iii) results of deformation experiments of bi-PST crystals prepared by DS processing and diffusion bonding, will be reported.

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Morphology and Texture of Chemical-Vapour-Deposited TiN Films

MRS Proceedings ◽

10.1557/proc-472-221 ◽

1997 ◽

Vol 472 ◽

Author(s):

Noboru Yoshikawa ◽

Shoji Taniguchi ◽

Atsushi Kikuchi

Keyword(s):

Crystal Orientation ◽

Chemical Vapour ◽

Deposition Process ◽

Grain Structure ◽

Similar Time ◽

Tin Films ◽

Grain Structures ◽

Structure Morphology ◽

Columnar Grains ◽

Zone Ii

ABSTRACTTiN films were obtained by Chemical Vapour Depositon (CVD) under different deposition conditions. Their grain structure, morphology and preferred crystal orientation were investigated. It was observed that well-defined columnar grams developed under conditions of atmospheric thermal CVD, giving rise to strong preferred orientations. In this study, grain structures of CVD-TiN films were classified with respect to the substrate temperature. Films of zone I structure were obtained at 1173K (0.35Tm), and those of zone II were obtained at 1223K (0.38Tm). Crystal shape of the zone II columnar grains was influenced by the partial pressure of TiCl4 (PTiCl4), and the crystal orientation of films was related to the crystal shapes. Columnar grains increased their thickness during deposition process under conditions of low PTiC14 and high temperature (>1250K). The increase rate of grain size had a similar time dependence to that of normal grain growth. The “quadrangular-shaped” and “star-shaped” columnar crystals were formed. They consisted of several crystals and contained twins. Their microstructures were observed in relation to their crystallographic features.

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