Nucleation of W-Rich Laves Phase Nanoparticles in Tempered Martensite Ferritic Steel During Long-Term Aging at Elevated Temperature

2020 ◽  
Vol 20 (7) ◽  
pp. 4489-4493
Author(s):  
Chungseok Kim
Keyword(s):  
Electron Microscopy ◽  
Elevated Temperature ◽  
Laves Phase ◽  
Vacuum Induction Melting ◽  
Ferritic Steels ◽  
Induction Melting ◽  
Tempered Martensite ◽  
Transmission Electron ◽  
The Matrix

The nucleation of W-rich Laves phase nanoparticles was studied during long-term aging at elevated temperature in tempered martensite ferritic steels (TMFS). The TMFS was fabricated by vacuum induction melting (VIM) process. The long-term aging tests are interrupted at various stages to simulate the different level of nucleation of intermetallic phases. In the present work, we employ scanning electron microscopy (SEM), Auger electron microscopy (AES), and transmission electron microscopy (TEM) to study the formation nucleation of Laves phase particles. We investigated the preference of Laves phase particles to nucleate next to M23C6 micrograin boundary carbides due to the segregation of W from the matrix to the micrograin boundaries.

Synthesis and Forming of Titanium Matrix Composites by Casting Route

2007 ◽  
Vol 334-335 ◽  
pp. 297-300
Author(s):  
Si Young Sung ◽  
Bong Jae Choi ◽  
Young Jig Kim
Keyword(s):  
Electron Microscopy ◽  
Melting Furnace ◽  
Vacuum Induction Melting ◽  
Induction Melting ◽  
Matrix Composites ◽  
Titanium Matrix ◽  
Titanium Matrix Composites ◽  
Electron Probe Micro Analyzer ◽  
Transmission Electron

The aim of this study is to evaluated the possibility of the in-situ synthesized (TiC+TiB) reinforced titanium matrix composites (TMCs) for the application of structural materials. In-situ synthesis and casting of TMCs were carried out in a vacuum induction melting furnace with Ti and B4C. The synthesized TMCs were characterized using scanning electron microscopy, an electron probe micro-analyzer and transmission electron microscopy, and evaluated through thermodynamic calculations. The spherical TiC plus needle-like and large, many-angled facet TiB reinforced TMCs can be synthesized with Ti and B4C by a melting route.

scholarly journals Influence of Inclusions on the Mechanical Properties of RAFM Steels Via Y and Ti Addition

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 851 ◽  
Author(s):  
Qiu ◽  
Zhan ◽  
Li ◽  
Yang ◽  
Qi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Oxide Particle ◽  
Vacuum Induction Melting ◽  
Induction Melting ◽  
Pinning Force ◽  
Impact Properties ◽  
Pinning Effect ◽  
Austenite Grain ◽  
Transmission Electron ◽  
Rafm Steel

The effects of the Y- and Ti-containing inclusions on the tensile and impact properties of reduced activation ferritic martensitic (RAFM) steels were evaluated. Four steels with different Y and Ti contents were produced via vacuum induction melting. The size and quantity of inclusions in the steels were analyzed using scanning electron microscopy, and the oxide particle formation mechanism was clarified. These inclusions helped to enhance the pinning effect of the austenite grain boundaries based on the Zener pinning force. The average prior austenite grain sizes, measured via the linear intercept method, were 12.34 (0 wt.% Ti), 9.35 (0.010 wt.% Ti), 10.22 (0.030 wt.% Ti), and 11.83 (0.050 wt.% Ti) μm for the four steels, in order of increasing Ti content, respectively. Transmission electron microscopy was conducted to observe the fine carbides. The strength and impact properties of the steel containing 0.010 wt.% Ti were improved, and the ductile-to-brittle-transition temperature was reduced to −70.5 °C. The tensile strength and impact toughness of the steel with 0.050 wt.% Ti were significantly reduced due to the coarsening of both the inclusions and grain size, as well as the precipitation of large TiN inclusions. The RAFM steel with approximately 0.015 wt.% Y and 0.010 wt.% Ti exhibited an optimized combination of microstructures, tensile properties, and impact properties among the four steels.

Study on the Microstructure and Properties of Low Cost TiFeAl Alloy

2013 ◽  
Vol 477-478 ◽  
pp. 1288-1292
Author(s):  
Bo Long Li ◽  
Tong Liu ◽  
Jie Yuan ◽  
Zuo Ren Nie
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Low Cost ◽  
High Strength ◽  
Al Alloys ◽  
Vacuum Induction Melting ◽  
Induction Melting ◽  
Β Phase ◽  
Transmission Electron ◽  
Solution Strengthening

The high strength and low cost Ti-Fe based alloy was produced by double vacuum induction melting method followed by hot deformation. The microstructure has been investigated by Optical Microscopy, Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM). The microstructure of as-forged alloy is composed of α and β phase without the precipitation of TiFe intermetallic compound. The Ti-Fe-Al alloys show good comprehensive mechanical properties, demonstrating ultimate tensile strength of 1100MPa and elongation above10%. The results indicate the Fe is a good candidate for solution strengthening and simultaneously increasing ductility in titanium alloys. Effect of the Fe and Al elements on the microstructure and mechanical properties have been discussed.

Laves Phase Formation in the Fe20Co18W Alloy Annealed at 800°C

2011 ◽  
Vol 172-174 ◽  
pp. 517-522 ◽  
Author(s):  
Paolo Galimberti ◽  
Sabine Lay ◽  
Annie Antoni-Zdziobek
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Transmission Electron Microscopy ◽  
Orientation Relationship ◽  
Phase Formation ◽  
Laves Phase ◽  
Transmission Electron ◽  
Precipitation Behaviour ◽  
The Matrix

The precipitation behaviour of the Fe20Co18W (wt%) alloy was studied by transmission electron microscopy during aging treatments at 800°C. The decomposition of the matrix produces the C14 phase. At the beginning of the heat treatment, the observation at the atom scale indicates that the structure of the precipitates does not coincide exactly with the Laves phase. Using the orientation relationship between the Fe based matrix and the precipitates it is shown that simple atomic shifts can lead to the transformation from the bcc matrix to the C14 Laves phase.

THE Z-PHASE IN 9Cr FERRITIC/MARTENSITIC HEAT RESISTANT STEEL

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1129-1134 ◽  
Author(s):  
FENGSHI YIN ◽  
FUXIA CHEN ◽  
XUEBO JIANG ◽  
BING XUE ◽  
LI ZHOU ◽  
...  
Keyword(s):  
Hot Forging ◽  
Vacuum Induction Melting ◽  
Induction Melting ◽  
Resistant Steel ◽  
Low Carbon ◽  
Heat Resistant Steel ◽  
Heat Resistant ◽  
The Matrix ◽  
Martensitic Lath

The precipitation behavior of Z -phase was investigated during long-term aging at 650°C in an ultra low carbon 9 Cr ferritic/martensitic heat resistant steel. The steel was prepared by vacuum induction melting followed by hot forging and rolling into a plate. The plate was normalized at 1100°C for 1h, cooled in air and tempered at 700°C for 1h. Bimodal nano-sized MX precipitates distribute densely and homogeneously in the matrix within martensitic lath after normalizing-and-tempering heat treatment. After aging at 650°C for 1200h, the Z -phase was found to nucleate on the larger nano-sized MX. The Z -phase and MX have the following orientation relationship: <112> Z - phase //<001> MX and [Formula: see text].

Microstructure in soft magnetic E3 (S1, Al) (Sendust) alloys

1988 ◽  
Vol 46 ◽  
pp. 770-771
Author(s):  
June D. Kim
Keyword(s):  
Electron Microscopy ◽  
Magnetic Properties ◽  
Ternary Phase Diagram ◽  
Vertical Tube ◽  
Vacuum Induction Melting ◽  
Induction Melting ◽  
Soft Magnetic ◽  
Quenching Temperature ◽  
Thin Foils ◽  
Vertical Tube Furnace

Iron-base alloys containing 8-11 wt.% Si, 4-8 wt.% Al, known as “Sendust” alloys, show excellent soft magnetic properties. These magnetic properties are strongly dependent on heat treatment conditions, especially on the quenching temperature following annealing. But little has been known about the microstructure and the Fe-Si-Al ternary phase diagram has not been established. In the present investigation, transmission electron microscopy (TEM) has been used to study the microstructure in a Sendust alloy as a function of temperature.An Fe-9.34 wt.% Si-5.34 wt.% Al (approximately Fe3Si0.6Al0.4) alloy was prepared by vacuum induction melting, and homogenized at 1,200°C for 5 hrs. Specimens were heat-treated in a vertical tube furnace in air, and the temperature was controlled to an accuracy of ±2°C. Thin foils for TEM observation were prepared by jet polishing using a mixture of perchloric acid 15% and acetic acid 85% at 10V and ∼13°C. Electron microscopy was performed using a Philips EM 301 microscope.

scholarly journals Oxygen Induced Phase Transformation in TC21 Alloy with a Lamellar Microstructure

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 163
Author(s):  
Shu Wang ◽  
Yilong Liang ◽  
Hao Sun ◽  
Xin Feng ◽  
Chaowen Huang
Keyword(s):  
Electron Microscopy ◽  
Phase Transformation ◽  
Oxygen Uptake ◽  
Titanium Alloys ◽  
Electron Backscatter Diffraction ◽  
Lamellar Microstructure ◽  
Α Phase ◽  
Transmission Electron ◽  
The Matrix ◽  
Oxygen Ingress

The main objective of the present study was to understand the oxygen ingress in titanium alloys at high temperatures. Investigations reveal that the oxygen diffusion layer (ODL) caused by oxygen ingress significantly affects the mechanical properties of titanium alloys. In the present study, the high-temperature oxygen ingress behavior of TC21 alloy with a lamellar microstructure was investigated. Microstructural characterizations were analyzed through optical microscopy (OM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). Obtained results demonstrate that oxygen-induced phase transformation not only enhances the precipitation of secondary α-phase (αs) and forms more primary α phase (αp), but also promotes the recrystallization of the ODL. It was found that as the temperature of oxygen uptake increases, the thickness of the ODL initially increases and then decreases. The maximum depth of the ODL was obtained for the oxygen uptake temperature of 960 °C. In addition, a gradient microstructure (αp + β + βtrans)/(αp + βtrans)/(αp + β) was observed in the experiment. Meanwhile, it was also found that the hardness and dislocation density in the ODL is higher than that that of the matrix.

scholarly journals The Effect of Long-Term Impact of Elevated Temperature on Changes in Microstructure and Mechanical Properties of HR3C Steel

2016 ◽  
Vol 61 (2) ◽  
pp. 761-766 ◽  
Author(s):  
A. Zieliński ◽  
M. Sroka ◽  
A. Hernas ◽  
M. Kremzer
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperature ◽  
X Ray ◽  
Qualitative And Quantitative ◽  
Microstructure And Mechanical Properties ◽  
Transmission Electron ◽  
Quantitative Identification ◽  
Working Parameters ◽  
Long Term Impact

Abstract The HR3C is a new steel for pressure components used in the construction of boilers with supercritical working parameters. In the HR3C steel, due to adding Nb and N, the compounds such as MX, CrNbN and M23C6 precipitate during service at elevated temperature, resulting in changes in mechanical properties. This paper presents the results of microstructure investigations after ageing at 650, 700 and 750 °C for 5,000 h. The microstructure investigations were carried out using scanning and transmission electron microscopy. The qualitative and quantitative identification of the existing precipitates was carried out using X-ray analysis of phase composition. The effect elevated temperature on microstructure and mechanical properties of the examined steel was described.

Microstructure Evolution and Mechanical Properties of an Al-Cu-Mg Alloy at Elevated Temperature

2014 ◽  
Vol 1004-1005 ◽  
pp. 148-153
Author(s):  
Min Hao ◽  
Ji Gang Ru ◽  
Ming Liu ◽  
Kun Zhang ◽  
Liang Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Elevated Temperature ◽  
Elevated Temperatures ◽  
Shear Fracture ◽  
S Phase ◽  
Mg Alloy ◽  
Transmission Electron ◽  
Fracture Features ◽  
Scanning Electron

Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were utilized to study the microstructure and mechanical behavior of an Al-Cu-Mg alloy after tensile test at 125°C, 150°C, 175°C and 200 °C, respectively. The yield strength and ultimate tensile strength decreased with the increase of temperature, while the elongation increased firstly and then decreased. The S and S′ precipitate after tension at elevated temperatures. When the temperature was higher than 175°C, the precipitate coarsens rapidly. The alloys displayed a shear fracture features at elevated temperature. The larger S′ and S phase coarsened and dropped which forming crack in the grain boundaries and precipitate interfaces, resulting in the decrease of the elongation of the alloy.

Atomic-scale structural and compositional analyses of Ruddlesden-Popper planar faults in AO-excess SrTiO3 (A = Sr2+, Ca2+, Ba2+) ceramics

2009 ◽  
Vol 24 (8) ◽  
pp. 2596-2604 ◽  
Author(s):  
Sašo Šturm ◽  
Makoto Shiojiri ◽  
Miran Čeh
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Dark Field ◽  
Atomic Scale ◽  
Transmission Electron ◽  
Initial Stage ◽  
Final Microstructure ◽  
Scanning Transmission ◽  
The Matrix ◽  
Annular Dark Field

The microstructure in AO-excess SrTiO3 (A = Sr2+, Ca2+, Ba2+) ceramics is strongly affected by the formation of Ruddlesden-Popper fault–rich (RP fault) lamellae, which are coherently intergrown with the matrix of the perovskite grains. We studied the structure and chemistry of RP faults by applying quantitative high-resolution transmission electron microscopy and high-angle annular dark-field scanning transmission electron microscopy analyses. We showed that the Sr2+ and Ca2+ dopant ions form RP faults during the initial stage of sintering. The final microstructure showed preferentially grown RP fault lamellae embedded in the central part of the anisotropic perovskite grains. In contrast, the dopant Ba2+ ions preferably substituted for Sr2+ in the SrTiO3 matrix by forming a BaxSr1−xTiO3 solid solution. The surplus of Sr2+ ions was compensated structurally in the later stages of sintering by the formation of SrO-rich RP faults. The resulting microstructure showed RP fault lamellae located at the surface of equiaxed BaxSr1-xTiO3 perovskite grains.

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