Effect of Low Cu Addition and Thermo-Mechanical History on Precipitation in Al-Mg-Si Alloys

2014 ◽  
Vol 794-796 ◽  
pp. 1014-1019 ◽  
Author(s):  
Takeshi Saito ◽  
Calin D. Marioara ◽  
Jostein Røyset ◽  
Randi Holmestad
Keyword(s):  
Heat Treatment ◽  
Cooling Rate ◽  
Solution Heat Treatment ◽  
Precipitation Hardening ◽  
Peak Hardness ◽  
Isothermal Heat Treatment ◽  
Slow Cooling ◽  
Transmission Electron ◽  
Material Hardness ◽  
Initial Hardness

The effect of cooling rate after solution heat treatment and its combination with 1% pre-deformation on precipitation hardening in two Al-Mg-Si alloys is investigated by transmission electron microscopy (TEM), and related to material hardness. Two alloys have been used, one Cu-free and the other with low Cu additions (~0.1 wt%), both having the same amounts of other solutes. A double peak hardness evolution during an isothermal heat treatment was observed with slow cooling after solution heat treatment. This effect was less pronounced in the Cu-added alloy. The 1% pre-deformation also made this effect less pronounced, but it led to faster initial hardness evolution and delayed over-aging. Maximum hardness was not influenced by cooling rate and the pre-deformation. Hardness was directly related to precipitate number densities.

Influence of Low Cu Addition on Quench Sensitivity in Al-Mg-Si Alloys

2014 ◽  
Vol 922 ◽  
pp. 616-621
Author(s):  
Takeshi Saito ◽  
Calin D. Marioara ◽  
Jostein Røyset ◽  
Randi Holmestad
Keyword(s):  
Heat Treatment ◽  
Solution Heat Treatment ◽  
The Other ◽  
Isothermal Heat Treatment ◽  
Maximum Hardness ◽  
Slow Cooling ◽  
Quench Sensitivity ◽  
Cooling Conditions ◽  
Transmission Electron ◽  
Material Hardness

Quench sensitivity in two Al-Mg-Si alloys, one Cu-free and the other with low Cu additions (~0.1 wt%), both having the same amounts of other solutes, has been investigated using transmission electron microscopy (TEM) and corresponding material hardness. A two stage hardness evolution during an isothermal heat treatment was observed with slow cooling after solution heat treatment. This effect was less pronounced in the Cu-added alloy. However maximum hardness was not influenced by cooling rate, which could be related to higher precipitate number densities and volume fractions. Both alloys were over-aged faster in the slow cooling conditions.

Precipitate and Age Hardening Response of As-Cast Mg-8Yb-0.5Zr Magnesium Alloy

2011 ◽  
Vol 399-401 ◽  
pp. 17-20
Author(s):  
Wen Bin Yu ◽  
Zhi Qian Chen ◽  
Mang Zhang ◽  
Zhou Yu
Keyword(s):  
Heat Treatment ◽  
Magnesium Alloy ◽  
Grain Boundaries ◽  
Microstructure Evolution ◽  
Solution Heat Treatment ◽  
Artificial Aging ◽  
Precipitation Hardening ◽  
Intermetallic Phase ◽  
Age Hardening ◽  
Maximum Hardness

The precipitation hardening response of as-cast Mg-8Yb-0.5Zr magnesium alloy was investigated in the present work. The microstructure evolution of the alloy illustrated that Mg2Yb intermetallic phase was dissolved by solution heat treatment at 520°C for 12 hours. An apparent precipitation hardening response in Mg-8Yb-0.5Zr was discovered after artificial aging at 150°C, with maximum hardness increment of about 80 percent at the peak condition. It was found that the precipitates of the alloy were in the shape of two conjoined cosh and globe about 50 nm, and precipitated preferentially on grain boundaries and dislocations.

The effect of grain size on microstructure and stress relaxation in polycrystalline Y1Ba2Cu3O7−δ

1989 ◽  
Vol 4 (2) ◽  
pp. 248-256 ◽  
Author(s):  
T. M. Shaw ◽  
S. L. Shinde ◽  
D. Dimos ◽  
R. F. Cook ◽  
P. R. Duncombe ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Transmission Electron Microscopy ◽  
Grain Size ◽  
Stress Relaxation ◽  
Optical Microscopy ◽  
Slow Cooling ◽  
Hierarchical Arrangement ◽  
Transmission Electron ◽  
Processing Variables

We have used transmission electron microscopy and optical microscopy to examine the effect that grain size and heat treatment have on twinning and microcracking in polycrystalline Y1Ba2Cu3O7−δ. It is shown that isothermal oxygenation heat treatments produce twin structures consisting of parallel twins, with a characteristic spacing that increases with increasing grain size. Slow cooling through the temperature range where the orthorhombic-to-tetragonal transformation induces twinning, however, produces a structure consisting of a hierarchical arrangement of intersecting twins, the scale of which appears to be independent of grain size. It is also shown that the microcracking induced by anisotropic changes in grain dimensions on cooling or during oxygenation can be suppressed if the grain size of the material is kept below about 1 μm. The results are examined in the light of current models for transformation twinning and microcracking and the models used to access the effect other processing variables such as oxygen content, doping or heat treatment may have on the microstructure of Y1Ba2Cu3O7−δ.

Effects of cooling rate on solution heat treatment of as-cast A356 alloy

2015 ◽  
Vol 25 (10) ◽  
pp. 3189-3196 ◽  
Author(s):  
Chang-lin YANG ◽  
Yuan-bing LI ◽  
Bo DANG ◽  
He-bin LÜ ◽  
Feng LIU
Keyword(s):  
Heat Treatment ◽  
Cooling Rate ◽  
Solution Heat Treatment ◽  
A356 Alloy

Connectivity and flux pinning improvements in Ag-clad BSCCO-2223 tapes produced by changes in the cooling rate

1997 ◽  
Vol 12 (11) ◽  
pp. 2997-3008 ◽  
Author(s):  
J. A. Parrell ◽  
D. C. Larbalestier ◽  
G. N. Riley ◽  
Q. Li ◽  
W. L. Carter ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Critical Temperature ◽  
Cooling Rate ◽  
Flux Pinning ◽  
Irreversibility Field ◽  
Superconducting Properties ◽  
Temperature Transition ◽  
Slow Cooling ◽  
Reaction Heat ◽  
Final Reaction

The rate at which Ag-clad (Bi, Pb)2Sr2Ca2Cu3Ox tapes are cooled from their final reaction heat treatment influences both the intergranular connectivity and intragranular flux pinning strength of the polycrystalline filaments. As the cooling rate from 825 °C to 730 °C in 7.5% O2 was decreased over a range of 5 °C/min to 0.005 °C/min, Jc (77 K, 0 T) increased from ∼8 to ∼24 kA/cm2, and the irreversibility field increased from, ∼120 to, ∼200 mT. The Jc (4.2 K, 0 T) increased in a similar fashion. Cooling slowly also sharpened the critical temperature transition and increased the critical onset temperature from 107 K to 109 K. These improvements in the superconducting properties occurred despite partial decomposition of the (Bi, Pb)2Sr2Ca2Cu3Ox phase into non-superconducting impurity phases during the slow cooling. A microstructural basis for these multiple effects is described.

scholarly journals The Effect of Cooling Rate after Homogenization on the Microstructure and Properties of 2017a Alloy Billets for Extrusion with Solution Heat Treatment on the Press

2016 ◽  
Vol 61 (3) ◽  
pp. 1663-1670
Author(s):  
A. Woźnicki ◽  
D. Leśniak ◽  
G. Włoch ◽  
P. Pałka ◽  
B. Leszczyńska-Madej ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Cooling Rate ◽  
Solution Heat Treatment ◽  
Rapid Heating ◽  
The Press ◽  
Large Particles ◽  
Rapid Dissolution ◽  
Alloy Microstructure ◽  
Fast Dissolution ◽  
Short Time

AbstractThe influence of cooling rate after homogenization on the 2017A alloy microstructure was analysed. The capability of the θ (Al2Cu) particles, precipitated during various homogenization coolings, for rapid dissolution was estimated. For this purpose, the DSC test was used to determine the effect of the cooling rate after homogenization on the course of melting during a rapid heating. Moreover, the samples after solution heat treatment (with short time annealing) and ageing, were subjected to the microstructure investigations and the microhardness of grains interiors measurements. It was found that cooling after homogenization at 160 °C/h is sufficient for precipitation of fine θ phase particles, which dissolve during the subsequent rapid heating. The cooling at 40 °C/h, causes the precipitation of θ phase in the form of large particles, incapable of further fast dissolution.

Feasibility Study on Die Quenching of AA2024 Aluminum Alloy Billet Using Servo Press

2014 ◽  
Vol 922 ◽  
pp. 286-291 ◽  
Author(s):  
Jae Yeol Jeon ◽  
Ryo Matsumoto ◽  
Hiroshi Utsunomiya
Keyword(s):  
Aluminum Alloy ◽  
Motion Control ◽  
Solution Heat Treatment ◽  
Precipitation Hardening ◽  
Peak Hardness ◽  
Precipitation Kinetics ◽  
Aging Behavior ◽  
Servo Press ◽  
Die Quenching ◽  
The Press

Die quenching of an AA2024 aluminum alloy billet was carried out using a servo press with ram motion control of WC-20mass%Co dies directly after solution heat treatment (SHT). The cylindrical billets were heated in an electric furnace and transferred to the press, then subjected to uniaxial compression with a reduction in height (Δh/h0) of 2%, 5% or 10% after SHT at 773 K or 823 K. The die quenching was successfully carried out without the precipitation hardening only on the billet after SHT at 823 K by sandwiching for 8 s. The subsequent artificial aging behavior at 463 K in an oil bath was investigated. It is found that the precipitation kinetics is accelerated in the die-quenched billets after SHT at 823 K. The peak hardness of the billet processed with 5% after SHT at 823 K is as high as that of the water-quenched billet, HV 149.0.

scholarly journals Study of the precipitation hardening process in recycled Al-Si-Cu cast alloys

2017 ◽  
Vol 62 (1) ◽  
pp. 397-403 ◽  
Author(s):  
L. Kuchariková ◽  
E. Tillová ◽  
M. Matvija ◽  
J. Belan ◽  
M. Chalupová
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Precipitation Hardening ◽  
Cast Alloy ◽  
Solution Treatment ◽  
Second Phase ◽  
Thin Foils ◽  
Transmission Electron ◽  
Different Temperatures ◽  
Cast Alloys

AbstractThe formation of extremely small uniformly dispersed particles of a second phase within the original phase matrix during heat treatment changed material properties. Therefore the characterization of precipitation had been investigated using high resolution transmission electron microscopy (TEM) and electron diffraction of thin foils for an AlSi9Cu3 cast alloy. For investigation the hardening effect onto mechanical properties of aluminium cast was used heat treatment, which consisted from solution treatment at 515°C / 4 hours (h), followed by quenching into water with temperature 50°C and artificial aging using different temperatures 170°C and 190°C with different holding time 2, 4, 8, 16, and 32 hours. The observations of microstructure and substructure reveals that precipitation hardening has caused great changes in size, morphology and distributions of structural components, the formation of precipitates of Cu phases, and the change of mechanical properties as well.

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