Monotectic Al–Bi–Sn alloys directionally solidified: Effects of Bi content, growth rate and cooling rate on the microstructural evolution and hardness

2015 ◽  
Vol 653 ◽  
pp. 243-254 ◽  
Author(s):  
Thiago A. Costa ◽  
Emmanuelle S. Freitas ◽  
Marcelino Dias ◽  
Crystopher Brito ◽  
Noé Cheung ◽  
...  
Keyword(s):  
Growth Rate ◽  
Cooling Rate ◽  
Microstructural Evolution ◽  
Directionally Solidified

scholarly journals Influence of thermal parameters on the dendritic arm spacing and the microhardness of Al-5.5wt.%Sn alloy directionally solidified

2014 ◽  
Vol 67 (2) ◽  
pp. 173-179 ◽  
Author(s):  
Angela de Jesus Vasconcelos ◽  
Cibele Vieira Arão da Silva ◽  
Antonio Luciano Seabra Moreira ◽  
Maria Adrina Paixão de Sousa da Silva ◽  
Otávio Fernandes Lima da Rocha
Keyword(s):  
Growth Rate ◽  
Aluminum Alloys ◽  
Cooling Rate ◽  
Thermal Parameters ◽  
The Other ◽  
Directionally Solidified ◽  
Dendritic Microstructure ◽  
Dendritic Network ◽  
Dendritic Arm Spacing ◽  
The Relationship

Al-Sn alloys are widely used in tribological applications. In this study, thermal, microstructural and microhardness (HV) analysis were carried out with an Al-5.5wt.%Sn alloy ingot produced by horizontal directional transient solidification. The main parameters analyzed include the growth rate (V L) and cooling rate (T R).These thermal parameters play a key role in the microstructural formation. The dendritic microstructure has been characterized by primary dendritic arm spacing (λ1) which was experimentally determined and correlated with V L, and T R. The behavior presented by the Al-5.5wt.%Sn alloy during solidification was similar to that of other aluminum alloys, i.e., the dendritic network became coarser with decreasing cooling rates, indicating that the immiscibility between aluminum and tin does not have a significant effect on the relationship between primary dendritic arm spacing and the cooling rate. The dependence of the microhardness on V L, T R and λ1 was also analyzed. It was found that for increasing values of T R, the values of HV decrease. On the other hand, the values of HV increase with increasing values of λ1.

Thermal Parameters, Tertiary Dendritic Growth and Microhardness of Directionally Solidified Al-3wt%Cu Alloy

2016 ◽  
Vol 869 ◽  
pp. 452-457 ◽  
Author(s):  
André Santos Barros ◽  
Maria Adrina Paixão de Souza da Silva ◽  
Otávio Fernandes Lima da Rocha ◽  
Antonio Luciano Seabra Moreira
Keyword(s):  
Growth Rate ◽  
Directional Solidification ◽  
Cooling Rate ◽  
Dendritic Growth ◽  
Solidification Process ◽  
Flow Conditions ◽  
Directionally Solidified ◽  
Cu Alloy ◽  
Cu Alloys ◽  
Transient Heat Flow

The main purpose of this paper is to evaluate both tertiary dendritic arm growth and microhardness of Al-3wt%Cu alloy during horizontal directional solidification under transient heat flow conditions. Experimental thermal profiles recorded during solidification process allowed to determine growth rate and cooling rate values which are associated with both tertiary dendritic arm spacings and microhardness. The results show that initial tertiary branches growth only occurs when a cooling rate value of 1.14 K/s is reached. Variation of tertiary spacings is expressed as-1.1 and-0.55 power law functions of growth rate and cooling rate, respectively. A comparative analysis with other studies published in the literature that analyze tertiary dendritic growth of Al-Cu alloys considering transient directional solidification is carried out. Dependence of microhardness on dendritic arrangement is evaluated by experimental laws of power and Hall-Petch types with a view to permitting the applicability of the resulting expressions.

MICROSTRUCTURAL EVOLUTION OF DIRECTIONALLY SOLIDIFIED Ni--BASED SUPERALLOY DZ125 UNDER PLANAR GROWTH

2010 ◽  
Vol 46 (9) ◽  
pp. 1075-1080 ◽  
Author(s):  
Zhixian MIN ◽  
Jun SHEN ◽  
Lingshui WANG ◽  
Zhourong FENG ◽  
Lin LIU ◽  
...  
Keyword(s):  
Microstructural Evolution ◽  
Directionally Solidified ◽  
Planar Growth

Thermal Parameters, Microstructure and Porosity During Transient Solidification of Ternary Al–Cu–Si Alloys

2012 ◽  
Vol 730-732 ◽  
pp. 883-888 ◽  
Author(s):  
Daniel J. Moutinho ◽  
Laércio G. Gomes ◽  
Otávio L. Rocha ◽  
Ivaldo L. Ferreira ◽  
Amauri Garcia
Keyword(s):  
Growth Rate ◽  
Chemical Composition ◽  
Cooling Rate ◽  
Tip Growth ◽  
Thermal Parameters ◽  
Volumetric Fraction ◽  
Dendritic Network ◽  
Intermetallic Particles ◽  
Casting Length

Solidification of ternary Al-Cu-Si alloys begins with the development of a complex dendritic network typified by primary (λ1) and secondary (λ2) dendrite arm spacings which depend on the chemical composition of the alloy and on the casting thermal parameters such as the growth rate and the cooling rate. These thermal parameters control the scale of dendritic arms, the size and distribution of porosity and intermetallic particles in the casting. In this paper, λ1and λ2were correlated with experimental thermal parameters i.e., the tip growth rate and the tip cooling rate. The porosity profile along the casting length has also been experimentally determined. The volumetric fraction of pores increase with the increase in alloying Si and with the increase in Fe concentration at the regions close to the casting cooled surface.

Dependence of Microstructures and Mechanical Properties on the Growth Rate and Composition in Directionally Solidified Mg-Gd Alloys

2022 ◽  
Vol 327 ◽  
pp. 82-97
Author(s):  
He Qin ◽  
Guang Yu Yang ◽  
Shi Feng Luo ◽  
Tong Bai ◽  
Wan Qi Jie
Keyword(s):  
Mechanical Properties ◽  
Growth Rate ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Dendritic Structure ◽  
Directionally Solidified ◽  
Dendrite Morphology ◽  
Microstructural Parameters ◽  
Wide Range ◽  
Microstructures And Mechanical Properties

Microstructures and mechanical properties of directionally solidified Mg-xGd (5.21, 7.96 and 9.58 wt.%) alloys were investigated at a wide range of growth rates (V = 10-200 μm/s) under the constant temperature gradient (G = 30 K/mm). The results showed that when the growth rate was 10 μm/s, different interface morphologies were observed in three tested alloys: cellular morphology for Mg-5.21Gd alloy, a mixed morphology of cellular structure and dendritic structure for Mg-7.96Gd alloy and dendrite morphology for Mg-9.58Gd alloy, respectively. Upon further increasing the growth rate, only dendrite morphology was exhibited in all experimental alloys. The microstructural parameters (λ1, λ2) decreased with increasing the growth rate for all the experimental alloy, and the measured λ1 and λ2 values were in good agreement with Trivedi model and Kattamis-Flemings model, respectively. Vickers hardness and the ultimate tensile strength increased with the increase of the growth rate and Gd content, while the elongation decreased gradually. Furthermore, the relationships between the hardness, ultimate tensile strength, the growth rate and the microstructural parameters were discussed and compared with the previous experimental results.

Microstructural Evolution and Coherent Islands

1992 ◽  
Vol 280 ◽  
Author(s):  
Jeff Drucker
Keyword(s):  
Growth Rate ◽  
Surface Diffusion ◽  
Microstructural Evolution ◽  
Rigid Substrate ◽  
Island Growth ◽  
Equilibrium Solubility

ABSTRACTMicrostructural evolution in systems containing strained islands (coherent, incoherent or both) is investigated. The growth rate of an individual island coarsening in an ensemble of strained islands is obtained by including elastic effects on surface diffusion of adatoms to and the equilibrium solubility of strained islands. For strained islands growing on a quasi-rigid substrate, coherent islands grow more slowly than incoherent islands of the same radius. Consequently, the island growth rate accelerates at the coherent to incoherent transition. The model agrees with recent experimental observations in Ge/Si(100) heteroepitaxy.

Microstructural Evolution during the Directional Transient Solidification of a Hypomonotectic Al-0.9wt%Pb Alloy

2012 ◽  
Vol 730-732 ◽  
pp. 829-834
Author(s):  
Adrina P. Silva ◽  
Pedro R. Goulart ◽  
José Eduardo Spinelli ◽  
Amauri Garcia
Keyword(s):  
Growth Rate ◽  
Heat Flow ◽  
Thermal Parameters ◽  
Cooling Curves ◽  
Flow Conditions ◽  
Directionally Solidified ◽  
Microstructural Transition ◽  
Transient Heat Flow ◽  
Growth Laws ◽  
Casting Length

In the present study a hypomonotectic Al-0.9wt%Pb alloy was directionally solidified under transient heat flow conditions and the microstructure evolution was analyzed. The solidification thermal parameters such as the growth rate, the cooling rate and the temperature gradient were experimentally determined by cooling curves recorded by thermocouples positioned along the casting length. The monotectic structure was characterized by metallography and a microstructural transition was observed. From the casting cooled surface up to a certain position in the casting the microstructure was characterized by well-distributed Pb-rich droplets in the aluminum-rich matrix, followed by a mixture of fibers and strings of pearls from this point to the top of the casting. The interphase spacing (λ) and the diameter of Pb-rich particles were also measured along the casting length and experimental growth laws relating these microstructural features to the experimental thermal parameters are proposed.

Effects of Melt Treatment on Dendrite Coherency of A357 Alloy

2011 ◽  
Vol 189-193 ◽  
pp. 3886-3890
Author(s):  
Zhong Wei Chen ◽  
Pei Chen ◽  
Li Fan
Keyword(s):  
Thermal Analysis ◽  
Growth Rate ◽  
Cooling Rate ◽  
Solid Fraction ◽  
Dendrite Growth ◽  
A357 Alloy ◽  
Dendrite Coherency Point ◽  
Melt Treatment ◽  
Coherency Point ◽  
Dendrite Coherency

The Dendrite Coherency Point (DCP) of A357 alloy was determined after different melt treatments by double thermocouples, and the coherency solid fraction (fscoh) was calculated by thermal analysis. The results of dendrite coherency properties show that fscoh values increase with increased cooling rate for A357 alloy. For A357 alloys, fscoh values increase after grain refined and melt superheat treatment. The coherency point was found to be dependent on not only the morphology of the dendrites but also the dendrite growth rate.

Sign in / Sign up

Export Citation Format

Share Document