The Experts below are selected from a list of 4920 Experts worldwide ranked by ideXlab platform
J Banhart - One of the best experts on this subject based on the ideXlab platform.
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positive effect of natural pre Ageing on precipitation hardening in al 0 44at mg 0 38at si alloy
Ultramicroscopy, 2009Co-Authors: Cynthia Sin Ting Chang, I Wieler, N Wanderka, J BanhartAbstract:Age hardening in a purely ternary Al-Mg0.4-Si0.4 (0.44 at% Mg, 0.38at%Si) alloy that is similar to AA6060 was investigated by hardness measurement, TEM and three-dimensional atom probe (3D-AP). In particular, the effect of natural pre-Ageing before Artificial Ageing, which is known to have a positive effect in this alloy, was studied by comparing three different conditions: natural Ageing only, Artificial Ageing for 1.5h at 180 degrees C only and combined natural pre-Ageing and subsequent Artificial Ageing for 1.5h at 180 degrees C. Natural Ageing influences the mechanical properties significantly. Naturally aged alloys exhibit a hardening response that is governed by the presence of small clusters. Subsequent Artificial Ageing of naturally aged specimens increases the value of peak hardness, which is attributed to the increase of the number density of needle-shaped precipitates as compared to the samples without natural Ageing. It is assumed that besides these precipitates, the small Si clusters formed at room-temperature storage remain stable during Artificial Ageing.
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positive effect of natural pre Ageing on precipitation hardening in al 0 44at mg 0 38at si alloy
Ultramicroscopy, 2009Co-Authors: Cynthia Sin Ting Chang, I Wieler, N Wanderka, J BanhartAbstract:Abstract Age hardening in a purely ternary Al-Mg0.4–Si0.4 (0.44 at% Mg, 0.38at%Si) alloy that is similar to AA6060 was investigated by hardness measurement, TEM and three-dimensional atom probe (3D-AP). In particular, the effect of natural pre-Ageing before Artificial Ageing, which is known to have a positive effect in this alloy, was studied by comparing three different conditions: natural Ageing only, Artificial Ageing for 1.5 h at 180 °C only and combined natural pre-Ageing and subsequent Artificial Ageing for 1.5 h at 180 °C. Natural Ageing influences the mechanical properties significantly. Naturally aged alloys exhibit a hardening response that is governed by the presence of small clusters. Subsequent Artificial Ageing of naturally aged specimens increases the value of peak hardness, which is attributed to the increase of the number density of needle-shaped precipitates as compared to the samples without natural Ageing. It is assumed that besides these precipitates, the small Si clusters formed at room-temperature storage remain stable during Artificial Ageing.
John Banhart - One of the best experts on this subject based on the ideXlab platform.
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natural and Artificial Ageing in aluminium alloys the role of excess vacancies
Acta Materialia, 2021Co-Authors: Zi Yang, John BanhartAbstract:Abstract Non-equilibrium excess vacancies quenched-in after solutionising age-hardenable aluminium alloys at high temperature are known to play an important role in precipitation at lower temperatures. However, knowledge is still lacking on the extent of the contribution to precipitation at various temperatures. In this work, we revisit this classical problem and study the role of excess vacancies in an Al-Mg-Si alloy in natural and Artificial Ageing experimentally by hardness measurements, differential scanning calorimetry, and positron annihilation lifetime spectroscopy. We then apply a precipitation model involving a simulation of vacancy loss and solute diffusion based on parameters calculated by first principles. The experiments show that excess vacancies are largely removed in the initial seconds of Artificial Ageing with hardly any corresponding hardening, i.e., subsequent hardening is triggered primarily by equilibrium vacancies unlike natural Ageing, where hardening is mainly driven by excess vacancies. We reproduce the anomaly that hardening for a given time can be faster at lower temperatures and explain this by the different activation energies of vacancy annihilation and solute diffusion. The role of excess vacancies demonstrated in Al-Mg-Si alloys could be similar in other age-hardenable alloys and hence be a universal phenomenon.
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microscopic aspects of Artificial Ageing in al mg si alloys
Social Science Research Network, 2019Co-Authors: Mazen Madanat, John Banhart, Meng Liu, Xingpu Zhang, Qianning Guo, Jakub CižekAbstract:Al-Mg-Si alloys with a low solute content (0.4 %Mg, 0.4 %Si) and higher contents (Mg+Si=1.4%, all in wt.%) were solutionised, quenched and then Artificially aged (AA) at 180 °C, after which positron annihilation lifetime spectroscopy was applied to obtain information about precipitation and vacancy evolution during Ageing. Hardness measurements were carried out to complement the measurements of positron lifetime. AA was carried out in four different heating media and allowed for varying the heating rate from 2.4 to 170 K/s. The main result of the study is that there is a competition between vacancy losses and precipitation. The more precipitation takes place before and during AA, the more vacancies are retained and act back on clustering. Higher solute content, slower heating to 180 °C, natural pre-Ageing before AA and slower quenching after solutionising were found to have a comparable effect explainable by pre-precipitation before AA.
Cynthia Sin Ting Chang - One of the best experts on this subject based on the ideXlab platform.
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positive effect of natural pre Ageing on precipitation hardening in al 0 44at mg 0 38at si alloy
Ultramicroscopy, 2009Co-Authors: Cynthia Sin Ting Chang, I Wieler, N Wanderka, J BanhartAbstract:Age hardening in a purely ternary Al-Mg0.4-Si0.4 (0.44 at% Mg, 0.38at%Si) alloy that is similar to AA6060 was investigated by hardness measurement, TEM and three-dimensional atom probe (3D-AP). In particular, the effect of natural pre-Ageing before Artificial Ageing, which is known to have a positive effect in this alloy, was studied by comparing three different conditions: natural Ageing only, Artificial Ageing for 1.5h at 180 degrees C only and combined natural pre-Ageing and subsequent Artificial Ageing for 1.5h at 180 degrees C. Natural Ageing influences the mechanical properties significantly. Naturally aged alloys exhibit a hardening response that is governed by the presence of small clusters. Subsequent Artificial Ageing of naturally aged specimens increases the value of peak hardness, which is attributed to the increase of the number density of needle-shaped precipitates as compared to the samples without natural Ageing. It is assumed that besides these precipitates, the small Si clusters formed at room-temperature storage remain stable during Artificial Ageing.
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positive effect of natural pre Ageing on precipitation hardening in al 0 44at mg 0 38at si alloy
Ultramicroscopy, 2009Co-Authors: Cynthia Sin Ting Chang, I Wieler, N Wanderka, J BanhartAbstract:Abstract Age hardening in a purely ternary Al-Mg0.4–Si0.4 (0.44 at% Mg, 0.38at%Si) alloy that is similar to AA6060 was investigated by hardness measurement, TEM and three-dimensional atom probe (3D-AP). In particular, the effect of natural pre-Ageing before Artificial Ageing, which is known to have a positive effect in this alloy, was studied by comparing three different conditions: natural Ageing only, Artificial Ageing for 1.5 h at 180 °C only and combined natural pre-Ageing and subsequent Artificial Ageing for 1.5 h at 180 °C. Natural Ageing influences the mechanical properties significantly. Naturally aged alloys exhibit a hardening response that is governed by the presence of small clusters. Subsequent Artificial Ageing of naturally aged specimens increases the value of peak hardness, which is attributed to the increase of the number density of needle-shaped precipitates as compared to the samples without natural Ageing. It is assumed that besides these precipitates, the small Si clusters formed at room-temperature storage remain stable during Artificial Ageing.
N Wanderka - One of the best experts on this subject based on the ideXlab platform.
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positive effect of natural pre Ageing on precipitation hardening in al 0 44at mg 0 38at si alloy
Ultramicroscopy, 2009Co-Authors: Cynthia Sin Ting Chang, I Wieler, N Wanderka, J BanhartAbstract:Age hardening in a purely ternary Al-Mg0.4-Si0.4 (0.44 at% Mg, 0.38at%Si) alloy that is similar to AA6060 was investigated by hardness measurement, TEM and three-dimensional atom probe (3D-AP). In particular, the effect of natural pre-Ageing before Artificial Ageing, which is known to have a positive effect in this alloy, was studied by comparing three different conditions: natural Ageing only, Artificial Ageing for 1.5h at 180 degrees C only and combined natural pre-Ageing and subsequent Artificial Ageing for 1.5h at 180 degrees C. Natural Ageing influences the mechanical properties significantly. Naturally aged alloys exhibit a hardening response that is governed by the presence of small clusters. Subsequent Artificial Ageing of naturally aged specimens increases the value of peak hardness, which is attributed to the increase of the number density of needle-shaped precipitates as compared to the samples without natural Ageing. It is assumed that besides these precipitates, the small Si clusters formed at room-temperature storage remain stable during Artificial Ageing.
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positive effect of natural pre Ageing on precipitation hardening in al 0 44at mg 0 38at si alloy
Ultramicroscopy, 2009Co-Authors: Cynthia Sin Ting Chang, I Wieler, N Wanderka, J BanhartAbstract:Abstract Age hardening in a purely ternary Al-Mg0.4–Si0.4 (0.44 at% Mg, 0.38at%Si) alloy that is similar to AA6060 was investigated by hardness measurement, TEM and three-dimensional atom probe (3D-AP). In particular, the effect of natural pre-Ageing before Artificial Ageing, which is known to have a positive effect in this alloy, was studied by comparing three different conditions: natural Ageing only, Artificial Ageing for 1.5 h at 180 °C only and combined natural pre-Ageing and subsequent Artificial Ageing for 1.5 h at 180 °C. Natural Ageing influences the mechanical properties significantly. Naturally aged alloys exhibit a hardening response that is governed by the presence of small clusters. Subsequent Artificial Ageing of naturally aged specimens increases the value of peak hardness, which is attributed to the increase of the number density of needle-shaped precipitates as compared to the samples without natural Ageing. It is assumed that besides these precipitates, the small Si clusters formed at room-temperature storage remain stable during Artificial Ageing.
I Wieler - One of the best experts on this subject based on the ideXlab platform.
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positive effect of natural pre Ageing on precipitation hardening in al 0 44at mg 0 38at si alloy
Ultramicroscopy, 2009Co-Authors: Cynthia Sin Ting Chang, I Wieler, N Wanderka, J BanhartAbstract:Age hardening in a purely ternary Al-Mg0.4-Si0.4 (0.44 at% Mg, 0.38at%Si) alloy that is similar to AA6060 was investigated by hardness measurement, TEM and three-dimensional atom probe (3D-AP). In particular, the effect of natural pre-Ageing before Artificial Ageing, which is known to have a positive effect in this alloy, was studied by comparing three different conditions: natural Ageing only, Artificial Ageing for 1.5h at 180 degrees C only and combined natural pre-Ageing and subsequent Artificial Ageing for 1.5h at 180 degrees C. Natural Ageing influences the mechanical properties significantly. Naturally aged alloys exhibit a hardening response that is governed by the presence of small clusters. Subsequent Artificial Ageing of naturally aged specimens increases the value of peak hardness, which is attributed to the increase of the number density of needle-shaped precipitates as compared to the samples without natural Ageing. It is assumed that besides these precipitates, the small Si clusters formed at room-temperature storage remain stable during Artificial Ageing.
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positive effect of natural pre Ageing on precipitation hardening in al 0 44at mg 0 38at si alloy
Ultramicroscopy, 2009Co-Authors: Cynthia Sin Ting Chang, I Wieler, N Wanderka, J BanhartAbstract:Abstract Age hardening in a purely ternary Al-Mg0.4–Si0.4 (0.44 at% Mg, 0.38at%Si) alloy that is similar to AA6060 was investigated by hardness measurement, TEM and three-dimensional atom probe (3D-AP). In particular, the effect of natural pre-Ageing before Artificial Ageing, which is known to have a positive effect in this alloy, was studied by comparing three different conditions: natural Ageing only, Artificial Ageing for 1.5 h at 180 °C only and combined natural pre-Ageing and subsequent Artificial Ageing for 1.5 h at 180 °C. Natural Ageing influences the mechanical properties significantly. Naturally aged alloys exhibit a hardening response that is governed by the presence of small clusters. Subsequent Artificial Ageing of naturally aged specimens increases the value of peak hardness, which is attributed to the increase of the number density of needle-shaped precipitates as compared to the samples without natural Ageing. It is assumed that besides these precipitates, the small Si clusters formed at room-temperature storage remain stable during Artificial Ageing.
