scholarly journals Scanning 3DXRD Measurement of Grain Growth, Stress, and Formation of Cu6Sn5 around a Tin Whisker during Heat Treatment

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 446 ◽  
Author(s):  
Johan Hektor ◽  
Stephen Hall ◽  
N. Henningsson ◽  
Jonas Engqvist ◽  
Matti Ristinmaa ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Grain Boundaries ◽  
Grain Growth ◽  
Hydrostatic Stress ◽  
Coincidence Site Lattice ◽  
Sample Surface ◽  
Growth Stress ◽  
Projection Algorithm ◽  
Tin Whisker ◽  
Tin Coating

The 3D microstructure around a tin whisker, and its evolution during heat treatment were studied using scanning 3DXRD. The shape of each grain in the sample was reconstructed using a filtered-back-projection algorithm. The local lattice parameters and grain orientations could then be refined, using forward modelling of the diffraction data, with a spatial resolution of 250 n m . It was found that the tin coating had a texture where grains were oriented such that their c-axes were predominantly parallel to the sample surface. Grains with other orientations were consumed by grain growth during the heat treatment. Most of the grain boundaries were found to have misorientations larger than 15 ∘ , and many coincidence site lattice (CSL) or other types of low-energy grain boundaries were identified. None of the grains with CSL grain boundaries were consumed by grain growth. During the heat treatment, growth of preexisting Cu6Sn5 occurred; these grains were indexed as a hexagonal η phase, which is usually documented to be stable only at temperatures exceeding 186 ∘ C . This indicates that the η phase can exist in a metastable state for long periods. The tin coating was found to be under compressive hydrostatic stress, with a negative gradient in hydrostatic stress extending outwards from the root of the whisker. Negative stress gradients are generally believed to play an essential role in providing the driving force for diffusion of material to the whisker root.

A Role of Low Energy Grain Boundaries in the Abnormal Grain Growth in Fe-3%Si Alloy

2011 ◽  
Vol 127 ◽  
pp. 89-94 ◽  
Author(s):  
Ye Chao Zhu ◽  
Jiong Hui Mao ◽  
Fa Tang Tan ◽  
Xue Liang Qiao
Keyword(s):  
Grain Boundaries ◽  
Grain Growth ◽  
Electron Backscatter Diffraction ◽  
Dominant Role ◽  
Coincidence Site Lattice ◽  
Diffraction Method ◽  
Abnormal Grain Growth ◽  
Low Energy ◽  
Backscatter Diffraction

Low energy grain boundaries were considered to be important in abnormal grain growth by theoretical deduction. The disorientation angles and coincidence site lattice grain boundaries distribution of more than 20 Goss grains and their neighboring matrix grains in primary recrystallized Fe-3%Si alloy were investigated using an electron backscatter diffraction method. It was found that the frequency of low energy grain boundaries of Goss grains which are more likely to abnormally grow are higher than their neighboring matrix grains, which indicated that low energy grain boundaries play a dominant role in the abnormal grain growth of Fe-3%Si alloy. The result meets well with the abnormal grain growth theory.

Grain Growth Impediment of Fe-Based Nanocomposites During Heat Treatment at Elevated Temperature

1995 ◽  
Vol 400 ◽  
Author(s):  
B. Huang ◽  
R.J. Perez ◽  
E.J. Lavernia
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Grain Boundaries ◽  
Grain Growth ◽  
Ostwald Ripening ◽  
Nanocrystalline Structure ◽  
Liquid Argon ◽  
High Thermal Stability ◽  
Additional Stabilization ◽  
Nanocrystalline Microstructure

AbstractCryogenic ball milling of Fe-10 wt.%Al in liquid argon is shown to produce a nanocrystalline microstructure with high thermal stability against grain growth. The experimental evidence suggests that this stability may originate from the presence of fine γ-Al2O3 particles which pin the Fe grain boundaries. In contrast, Fe3O4 particles formed during cryomilling of Fe in liquid nitrogen were not able to impede grain growth during consolidation at 823 K. The interactions between the γ-Al2O3 particles and the grain boundaries during growth may be described by Gladman's theory. Additional stabilization against grain growth may have been provided by the presence of Al at the Fe grain boundaries. Following annealing at 1223 K, the grain size of the Fe-10 wt.%Al powders cryomilled in liquid argon was 13.3 ± 7.9 nm, but it exceeded 1700 nm following annealing at 1373 K. The loss of nanocrystalline structure may be attributed to the Ostwald ripening of γ-Al2O3 particles, resulting in abnormal grain growth.

The Impact of Pre-Silicidation Heat Treatment and Dopant Effects on the Thermal Stability of Cosi2 Polycide During Rapid Thermal Annealing

1993 ◽  
Vol 303 ◽  
Author(s):  
W. Chen ◽  
J. Lin ◽  
S. Banerjee ◽  
J. Lee
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Ion Implantation ◽  
Grain Boundaries ◽  
Grain Growth ◽  
Silicon Substrate ◽  
Amorphous Si ◽  
Si Films ◽  
The Impact ◽  
Thermal Stability Of

ABSTRACTThe effects of heat treatment of polysilicon and amorphous Si films on their microstructure and thermal stability of polycides formed on these films have been studied. The number of grain boundaries decreases after pre-silicidation heat treatment in polysilicon due to grain growth but increases in amorphous Si due to nucleation. Since the thermal stability of CoSi2 polycide films was found to be closely related to the number of grain boundaries in the underlying silicon substrate, pre-silicidation heat treatments degrade the thermal stability of CoSi2 on as-deposited amorphous Si and improve the thermal stability of CoSi2 on asdeposited polysilicon. Doping does not have as pronounced an effects as substrate microstructure on CoSi21 polycide thermal stability, especially when dopants are introduced after silicidation by ion implantation.

scholarly journals A Comparative Study of Acicular Ferrite Transformation Behavior between Surface and Interior in a Low C–Mn Steel by HT-LSCM

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 699
Author(s):  
Xiaojin Liu ◽  
Guo Yuan ◽  
Raja. Devesh Kumar Misra ◽  
Guodong Wang
Keyword(s):  
Grain Boundaries ◽  
Cooling Rate ◽  
Acicular Ferrite ◽  
Laser Scanning ◽  
Sample Surface ◽  
Surface Microstructure ◽  
In Situ Observation ◽  
Low Carbon ◽  
Transformation Behavior ◽  
Ferrite Transformation

In this study, the acicular ferrite transformation behavior of a Ti–Ca deoxidized low carbon steel was studied using a high-temperature laser scanning confocal microscopy (HT-LSCM). The in situ observation of the transformation behavior on the sample surface with different cooling rates was achieved by HT-LSCM. The microstructure between the surface and interior of the HT-LSCM sample was compared. The results showed that Ti–Ca oxide particles were effective sites for acicular ferrite (AF) nucleation. The start transformation temperature at grain boundaries and intragranular particles decreased with an increase in cooling rate, but the AF nucleation rate increased and the surface microstructure was more interlocked. The sample surface microstructure obtained at 3 °C/s was dominated by ferrite side plates, while the ferrite nucleating sites transferred from grain boundaries to intragranular particles when the cooling rate was 15 °C/s. Moreover, it was interesting that the microstructure and microhardness of the sample surface and interior were different. The AF dominating microstructure, obtained in the sample interior, was much finer than the sample surface, and the microhardness of the sample surface was much lower than the sample interior. The combined factors led to a coarse size of AF on the sample surface. AF formed at a higher temperature resulted in the coarse size. The available particles for AF nucleation on the sample surface were quite limited, such that hard impingement between AF plates was much weaker than that in the sample interior. In addition, the transformation stress in austenite on the sample surface could be largely released, which contributed to a coarser AF plate size. The coarse grain size, low dislocation concentration and low carbon content led to lower hardness on the sample surface.

Microstructure and Texture Evolution in Nickel during Accumulative Roll Bonding

2016 ◽  
Vol 879 ◽  
pp. 454-458 ◽  
Author(s):  
Jia Qi Duan ◽  
Md Zakaria Quadir ◽  
Michael Ferry
Keyword(s):  
Grain Boundaries ◽  
Accumulative Roll Bonding ◽  
Texture Evolution ◽  
Shear Bands ◽  
Rolling Direction ◽  
Sample Surface ◽  
Deformation Texture ◽  
Roll Bonding ◽  
Equiaxed Grains ◽  
Electron Back Scattered Diffraction

Microstructure and texture evolution of commercially pure Ni processed by accumulative roll-bonding (ARB) up to eight cycles were studied using electron back scattered diffraction (EBSD). During ARB processing, the original coarse equiaxed grains were gradually transformed into refined lamellar grains along the rolling direction (RD). Shear bands started forming after three cycles. The fraction of low angle grain boundaries (LAGBs) increased after the first and second cycle because of orientation spreading within the original grains. However, their fraction decreased with the evolution of high angle grain boundaries (HAGBs) during subsequent deformations, until saturation was reached after six cycles. Overall, the typical deformation texture components (S, Copper and Brass) were enhanced up to six ARB cycles and then only Copper was further strengthened. At higher cycles a higher Copper concentration was found near sample surface than the interiors due to a high frictional shear of ARB processing.

Microstructure of Polycrystalline MgO Penetrated by a Silicate Liquid

1996 ◽  
Vol 2 (3) ◽  
pp. 113-128 ◽  
Author(s):  
Sundar Ramamurthy ◽  
Michael P. Mallamaci ◽  
Catherine M. Zimmerman ◽  
C. Barry Carter ◽  
Peter R. Duncombe ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Grain Growth ◽  
Glassy Phase ◽  
Silicate Liquid ◽  
Two Phase ◽  
The Matrix ◽  
Devitrification Process ◽  
Phase Mixture

Dense, polycrystalline MgO was infiltrated with monticellite (CaMgSiO4) liquid to study the penetration of liquid along the grain boundaries of MgO. Grain growth was found to be restricted with increasing amounts of liquid. The inter-granular regions were generally found to be comprised of a two-phase mixture: crystalline monticellite and a glassy phase rich in the impurities present in the starting MgO material. MgO grains act as seeding agents for the crystallization of monticellite. The location and composition of the glassy phase with respect to the MgO grains emphasizes the role of intergranular liquid during the devitrification process in “snowplowing” impurities present in the matrix.

The measuring system for monitoring the microarc heating process during surface hardening of steel products

2021 ◽  
pp. 33-39
Author(s):  
Makar S. Stepanov ◽  
rina G. Koshlyakova
Keyword(s):  
Heat Treatment ◽  
Mathematical Model ◽  
Electric Current ◽  
Measurement Method ◽  
Sample Surface ◽  
Steel Sample ◽  
Measuring System ◽  
Heating Process ◽  
Carbon Powder ◽  
Measured Temperature

The accelerated heat treatment during steel products hardening technology has been investigated. The possibility of measuring the temperature of steel products by thermoelectric platinum-platinum-rhodium thermocouple under microarc heating conditions is analyzed. During the experiments, working junctions of two S-type thermocouples: working and standard, were coined into the sample surface at the same level. The free thermocouples ends were connected to a digital multimeter and a personal computer. It was determined that 5 factors affect the measurement results: the electric current strength in the circuit, carbon powder, calibration, number of repeated measurement cycles, and a thermocouple copy. When planning the experiment, the concept of conducting a step-by-step nested experiment was used. Variance analysis method was used to process the experimental results. The measurement method precision parameters were calculated: repeatability and reproducibility. A linear mathematical model linking the measurement method reproducibility index with the measured temperature value has been obtained. A linear mathematical model is obtained that relates the reproducibility index of the measurement method to the measured temperature value. A measuring system for the experimental determination of the temperature of a steel sample is proposed and its application is justified for different electric current densities on the sample surface and varying duration of microarc heating. The possibilities of selecting and controlling the microarc heating modes depending on the required temperature of the heat treatment of the steel product are determined.

Recovery, Recrystallization, and Grain-Growth

2019 ◽  
Vol 41 (1) ◽  
pp. 1-1
Author(s):  
Iqra Zubair Awan Iqra Zubair Awan
Keyword(s):  
Mechanical Properties ◽  
State Physics ◽  
Heat Treatment ◽  
Grain Growth ◽  
Structural Damage ◽  
Physical And Mechanical Properties ◽  
Mechanical Deformation ◽  
Solid State Physics ◽  
Science And Engineering ◽  
Thermally Activated

This is a brief review of the important phenomena of recovery, recrystallization as well as grain-growth. The three mentioned phenomena are the mechanisms by which metals and alloys fix the structural damage introduced by the mechanical deformation and, as a consequence, in the physical and mechanical properties. These rehabilitation mechanisms are thermally activated. For this process, the materials have to be heated and any such heat-treatment is meant to reduce deformation-induced break is termed annealing. Other or different heat-treatments lead to recovery and recrystallization. It is rather strange that, though these phenomena are extremely important in metallurgical science and engineering, not so much work has been done as that in corrosion and shape memory technologies. An attempt has been made here to summarize all important aspects of these phenomena for the benefits of students of metallurgy, chemistry and solid state physics.

Fracture Strengths of Individual Grain Boundaries in Ni3Ai Using a Miniaturized Disk Bend Test

1991 ◽  
Vol 238 ◽  
Author(s):  
Douglas E. Meyers ◽  
Alan J. Ardell
Keyword(s):  
Plastic Deformation ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Grain Growth ◽  
Coincident Site Lattice ◽  
Bend Test ◽  
High Angle ◽  
Load Drop ◽  
Site Lattice ◽  
Special Boundaries

ABSTRACTThe results of our initial efforts at measuring the fracture strengths of grain boundaries In Ni3Al using a miniaturized disk-bend test are presented. The samples tested were 3 mm in diameter and between 150 and 300 μm thick. An Ingot of directlonally-solidlfled, boron-free Ni3Al containing 24% Al was annealed between 1300 and 1350 °C to induce grain growth, producing many grain boundaries In excess of 1.5 mm in length. Specimens were cut from these In such a way that one long grain boundary was located near a diameter of the specimen. The relative orientations of the grains on either side of the boundary were determined from electron channeling patterns. Low-angle boundaries are so strong they do not fracture; Instead the samples deform In a completely ductile manner. High-angle boundaries always fracture, but only after considerable plastic deformation of the two grains flanking them. Fracture is Indicated by a load drop in the load vs. displacement curves. A method involving extrapolation of the elastic portion of these curves to the displacement at fracture is used to estimate the fracture stresses. This procedure yields consistent values of the fracture strengths of high-angle boundaries. The measured stresses are large (∼2 to 3 GPa), but considerably smaller than those required for the fracture of special boundaries, as predicted by computer simulations. No correlation was found between the fracture stresses or loads and the geometry of the high-angle boundaries, many of which are close to, but deviate from, coincident site lattice orientations.

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