Microstructural evolution and mechanical characterization for the A508–3 steel before and after phase transition

Microalloyed steels are used in the forging of many automotive parts like crankshafts and connecting rods. They are hot worked in a sequence of stages that includes the heating to the soaking temperature, followed by forging steps, and finally the controlled cooling to define the microstructure and mechanical properties. In this work it was investigated the thermomechanical behavior and the microstructural evolution of a Ti-V microalloyed steel in the phase transition region. Torsion tests were done with multiple steps with true strain equal to 0.26 in each step. After each torsion step the samples were continuous cooled for 15 seconds to simulate hot forging conditions. These tests provided results for the temperature at the beginning of the phase transformation, and allowed to analyze the microstructural changes. Also, workability tests were held to analyze the microstructural evolution by optical and scanning electron microscopy. Results from the torsion tests showed that the temperature for the beginning of phase transformation is about 700 ºC. Workability tests held at 700 ºC followed by water-cooling presented microstructures with different regions: strain hardened, and static and dynamic recrystallized. Workability tests at 700 ºC followed by air-cooling showed a complex microstructure with ferrite, bainite and martensite, while tests at 650 and 600 ºC followed by water-cooling showed a microstructure with allotriomorphic ferrite present in the grain boundaries of the previous austenite.

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The Influence of Li+ on the Sintering of Cordierite Glass Ceramic

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.336-338.1859 ◽

2007 ◽

Vol 336-338 ◽

pp. 1859-1861 ◽

Cited By ~ 2

Author(s):

Han Feng Wang ◽

He Ping Zhou

Keyword(s):

Phase Transition ◽

Dielectric Constant ◽

Expansion Coefficient ◽

Microstructural Evolution ◽

Glass Ceramic ◽

Sol Gel ◽

Nucleating Agent ◽

Cordierite Glass ◽

Gel Processing

The effects of Li+ addition on the sintering and microstructural evolution of cordierite were analyzed. As nucleating agent, the Li+ additive decreased the expansion coefficient and dielectric constant. The doping of Li+ was found to block the phase transition from μ-cordierite to α-cordierite and increase sintering temperatures. The effect of Li+ on the activation of cordierite can be attributed to the nucleation of cordierite. Too much Li+ will inhibit the cordierite crystallization and encourage amblygonite crystallization. Cordierite powders were prepared by sol-gel processing.

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Microstructural Evolution of Aluminum Interconnects During Post-Pattern Anneals: Correlation to Improved Em Lifetime

MRS Proceedings ◽

10.1557/proc-338-333 ◽

1994 ◽

Vol 338 ◽

Cited By ~ 4

Author(s):

B. Miner ◽

E.A. Atakov ◽

A. Shepela ◽

S. Bill

Keyword(s):

Grain Boundary ◽

Microstructural Evolution ◽

Triple Point ◽

Length Distribution ◽

Microstructural Parameters ◽

Statistical Measures ◽

Before And After ◽

Triple Points ◽

Aluminum Interconnects ◽

Cluster Length

ABSTRACTThe number of Al triple point junctions (Ntp) correlates inversely to electromigration lifetimes for partially bamboo interconnects that fail by grain boundary (GB) diffusion. This work emphasizes the evolution of statistical microstructural parameters, Ntp and cluster length distribution, during post-pattern anneals. In addition to statistical measures, the structure of specific clusters before and after anneal is compared from TEM images of the same area of the same sample.Each post-pattern anneal lowers Ntp and shortens the length of individual polycrystalline segments, but with diminishing returns for subsequent anneals. With a TiN capping layer, the statistical microstructural improvement is less but the longest clusters, those most probable as failure sites, lose triple points during anneal. The distribution of cluster lengths is characteristic for a process.

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Microstructural Evolution and Mechanical Evaluation of a Laser-Induced Composite Coating on a Ni-Based Superalloy during Thermal Exposure

Materials ◽

10.3390/ma12091439 ◽

2019 ◽

Vol 12 (9) ◽

pp. 1439

Author(s):

Yuebing Li ◽

Yanming He ◽

Chuanyang Lu ◽

Wenjian Zheng ◽

Jianguo Yang ◽

...

Keyword(s):

Microstructural Evolution ◽

Mechanical Performance ◽

Volume Fraction ◽

Thermal Exposure ◽

Eutectic Structure ◽

Laser Surface ◽

Microstructural Stability ◽

Coating Materials ◽

Before And After ◽

Surface Modified

A Ni–17Mo–7Cr-based superalloy was laser surface-modified to improve its tribological properties. Si particles were employed as coating materials. Si melted on the surface of the alloy during the process, triggering the formation of Mo6Ni6C carbides and Ni–Si intermetallics. A defect-free coating obtained was mostly made up of primary Mo6Ni6C and γ-Ni31Si12, as well as a eutectic structure of β1-Ni3Si and α-Ni-based solid solution (α-Ni (s.s)). The volume fraction of hard reinforcements (Mo6Ni6C, γ-Ni31Si12, and β1-Ni3Si) reached up to 85% in the coating. High-temperature microstructural stability of the coating was investigated by aging the coating at 1073 K for 240–480 h, to reveal its microstructural evolution. In addition, the mechanical performance of the coating was investigated. The nanoscale elastic modulus and hardness of Mo6Ni6C, γ-Ni31Si12, and α-Ni (s.s) were characterized using the nanoindentation tests. The nanoscratch tests were performed to measure the local wear resistance of the coating. Lastly, the Vickers hardness distribution across the cross-section of the coating before and after thermal exposure was compared. The work performed provides basic information understanding the microstructural evolution and mechanical performance of laser-induced coatings on Ni-based superalloys.

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Фазовый переход полупроводник--суперионик в пленках сульфида серебра

Физика твердого тела ◽

10.21883/ftt.2020.12.50218.152 ◽

2020 ◽

Vol 62 (12) ◽

pp. 2138

Author(s):

А.В. Ильинский ◽

Р.А. Кастро ◽

М.Э. Пашкевич ◽

И.О. Попова ◽

Е.Б. Шадрин

Keyword(s):

Experimental Data ◽

Thin Films ◽

Phase Transition ◽

Complex Impedance ◽

Silver Sulfide ◽

Electrical Circuit ◽

Cole Diagram ◽

Before And After ◽

Superionic Phase Transition ◽

Frequency Dependences

Frequency dependences of dielectric loss tangent tanδ (f) and Cole-Cole diagram of thin films of silver sulfide at various temperatures in the range 0-200 ° C were studied. A comparison of experimental data with the results of calculation of electrical circuit complex impedance of Ag2S samples is made. The comparison is made for temperatures before and after semiconductor-superionic phase transition. Based on the analysis of experimental results and literature data, a microscopic model of the phase transition in Ag2S is proposed.

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MICROSTRUCTURAL EVOLUTION AND RESIDUAL STRESSES OF AIR-PLASMA SPRAYED THERMAL BARRIER COATINGS UNDER THERMAL EXPOSURE

Surface Review and Letters ◽

10.1142/s0218625x10013965 ◽

2010 ◽

Vol 17 (03) ◽

pp. 337-343 ◽

Cited By ~ 3

Author(s):

JAE-YOUNG KWON ◽

JAE-HYOUN KIM ◽

SANG-YEOP LEE ◽

YEON-GIL JUNG ◽

HYUN CHO ◽

...

Keyword(s):

Thermal Barrier Coatings ◽

Microstructural Evolution ◽

Thermal Exposure ◽

Thermally Grown Oxide ◽

Thermal Barrier ◽

Air Plasma ◽

Barrier Coatings ◽

Before And After ◽

Peak Areas ◽

Plasma Sprayed

Microstructural evolution and fracture behavior of zirconia ( ZrO2 )-based thermal barrier coatings (TBCs) were investigated under thermal exposure. New ZrO 2 granule with 8 wt.% yttria ( Y2O3 ) with a deformed hollow morphology was developed through a spray drying process and employed to prepare TBCs. The thermal exposure tests were conducted at 1210°C with a dwell time of 100 h till 800 h. The residual stress at the interface between top coat and thermally grown oxide (TGO) layer was measured using a nanoindentation technique before and after thermal exposure. Vertical cracks on the top coat were newly formed and interlamellar cracks at the interface were enhanced after the thermal exposure of 800 h. Especially, partial delamination was observed at the interface after the thermal exposure of 800 h in TBC samples tested. The microstructural evolution in the top coat could be defined through load–displacement curves, showing a higher load or a less displacement after the thermal exposure of 800 h. The stress state was strongly dependent on the TGO geometry, resulting in the compressive stresses at the "valleys" or the "troughs," and the tensile stresses at the "crests" or peak areas, in the ranges of -500 to -75 MPa and of +168 to + 24 MPa, respectively. These stress terms incorporated with resintering during thermal exposure affected the mechanical properties such as hardness and elastic modulus of the top coat.

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Microstructural Evolution of Pb(Zr,Ti)O3 Ceramics Using Electron Paramagnetic Resonance

MRS Proceedings ◽

10.1557/proc-310-3 ◽

1993 ◽

Vol 310 ◽

Cited By ~ 2

Author(s):

W. L. Warren ◽

B. A. Tuttle ◽

R. W. Schwartz ◽

W. F. Hammetter ◽

D. C. Goodnow ◽

...

Keyword(s):

Electron Paramagnetic Resonance ◽

Microstructural Evolution ◽

Lead Zirconate Titanate ◽

Perovskite Phase ◽

Lead Zirconate ◽

Solution Chemistry ◽

Paramagnetic Resonance ◽

Before And After ◽

High Concentrations ◽

Electron Paramagnetic

AbstractUsing electron paramagnetic resonance (EPR) we have followed the microstructural evolution with temperature of lead zirconate titanate (PZT) ceramics from the amorphous to the perovskite phase. A number of paramagnetic point defects were identified (Carbon, Pb+3, and Ti+3) while traversing the evolution of these ceramics during various heat treatments both before and after optical illumination. Perhaps the most important finding is that the Pb+3 and Ti+3 centers can only be optically created in the perovskite materials, thereby, showing that they are not associated with the amorphous or the pyrochlore phases. It is also found that EPR signals attributed to carbon radicals are present in fairly high concentrations (4 × 1017/cm3) if the solution chemistry derived PZT materials are annealed in an oxygen deficient ambient (0.1% O2) at 650°C.

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