Wyniki wyszukiwania - BazTech

1

Recent advances in the kinetics of normal/abnormal grain growth: a review

Najafkhani Fateme, Kheiri Sara, Pourbahari Bita, Mirzadeh Hamed

Archives of Civil and Mechanical Engineering

|

2021

|

Vol. 21, no. 1

483--502

EN

Recent progress in the kinetics of grain coarsening and abnormal grain growth (AGG) is presented in this overview article. The factors affecting the kinetics of grain growth is reviewed with the emphasis on the recent findings on the solute drag and Zener pinning effects as well as the special case of duplex alloys, where the latter is discussed for the behavior of dual-phase steels during intercritical annealing. The common isothermal kinetics models for grain growth are listed, which is followed by the critical discussion on the simplifications and the commonly used methods for the determination of grain growth exponent (n) and activation energy (Q). The obtained values of n and Q for several classes of important engineering alloys such as microalloyed steels, stainless steels, magnesium alloys, aluminum alloys, titanium alloys, and high-entropy alloys are summarized with the discussion on the obtained values of kinetics parameters and their deviation from the theoretical expectations. Finally, the factors leading to AGG (such as the coarsening and dissolution of pinning particles and the crystallographic texture), the proposed mechanisms (such as the solid-state wetting and the grain boundary faceting/defaceting phenomena), and the kinetics of AGG (based on the empirical power law and the similarity of AGG to primary recrystallization in the form of secondary recrystallization) are reviewed. This overview can shed light on the understanding of grain growth and its effects.

2

Microstructure and Texture Evolution in Temper Rolled Fe-Si Steels with New System Nano-Inhibitors under the Dynamic Annealing Conditions

Kováč F., Petryshynets I., Horňak P.

Archives of Metallurgy and Materials

|

2017

|

Vol. 62, iss. 3

1727--1732

EN

This work investigates the microstructure and texture evolution in grain-oriented electrotechnical steel with a new inhibition system based on vanadium carbides nano-particles. The novel approach for the preparation of this steel with appropriate final magnetic properties combines not only nanoinhibitors based on the vanadium carbides precipitations but also includes straininduced grain growth mechanism in combination with dynamic continuous annealing during the secondary recrystallization. The experimental grain-oriented steel with proposed new chemical composition was prepared in laboratory conditions. The texture analysis has shown that suggested procedure led the formation of sufficiently strong {110}<001> Goss texture during the short time period of a final annealing process, which is comparable to that obtained in the conventionally treated grain-oriented steels.

3

A model for abnormal grain growth in nano-crystalline materials based on Zener drag force

Razavi-Tousi S. S., Yazdani-Rad R., Manafi S. A.

Archives of Metallurgy and Materials

|

2012

|

Vol. 57, iss. 1

79-85

EN

Abnormal grain growth of a matrix in which normal grain growth has stagnated due to the presence of fine incoherent ceramic particles is studied. A balance between driving and retarding forces is used as the criteria for estimating the steady state. Random and non-random approaches are applied for coarse and nano-grained structure respectively.

PL

Badano nieprawidłowy wzrost ziaren w materiale, w którym prawidłowy wzrost ziaren został zahamowany z powodu obecności drobnych cząsteczek ceramicznych. Równowaga pomiędzy siłami pędną i opóżniającą zostały przyjęte jako kryterium oszacowania stanu równowagi. Zastosowano przypadkowe i nieprzypadkowe podejście odpowiednio do struktury grubo i drobnoziarnistej.

4

Acoustic-mechanical and microscopic investigation of corundum material

Ranachowski P., Rejmund F., Pawełek A., Piątkowski A.

Archives of Acoustics

|

2007

|

Vol. 32, No. 4

963--969

EN

This paper presents the results of acoustic emission (AE) measurements of samples under compressive stress. Additional research, concerning structure and parameters of the material, were performed using microscopic and ultrasonic methods. The object of investigation were samples of corundum material C 799 type. The content of alumina in investigated material was equal to 99.7%. The corundum materials demonstrate high mechanical, thermomechanical as well as grindability resistance and find wide application in production of modern technical devices. The aim of study was recognition of stages of degradation processes of the corundum structure. The analysis of AE results pointed out diversified strength and mechanical-acoustic characteristics of particular samples. It was stated during microscopic investigation that the main reason for this effect is due to different grains size and their spatial distribution. The authors consider the abnormal grain growth (AGG) phenomenon as a reason of inhomogeneities of the corundum structures in particular samples. This effect occurs at longer sintering term, especially for fast temperature growth. AGG phenomenon has random character and up to now is not explained in satisfying way.