•Intermetallic particles of Al4Si4Yb/Al10Si4Yb and Al15Cu2Si2Gd phases were identified.•Due to the addition of Zr- and Yb- or Gd in alloys, YS is increased by 50–60 MPa.•Calculation size the ...dispersoids in the investigated alloys should be with of 20–40 nm.•The compression YS significantly increased in the rare earth metals doped alloys.
The microstructure and properties of the Al-5Si-1.3Cu-0.4 Mg-0.15Zr alloys with Yb or Gd additives were investigated. Al4Si4Yb/Al10Si4Yb and Al15Cu2Si2Gd eutectic phases were identified in the investigated alloys. The compression YS at room temperature and 200 °C significantly increased in the rare earth metals doped alloys in the quenched and aged state.
The in situ synthesis of titanium carbide reinforcing nanoparticles from nanodiamond precursors inside an aluminum or a copper matrix is developed in the frame of the present study. The starting ...materials for the synthesis were commercially available powders of aluminum or copper for matrix formation and titanium and nanodiamond powders as the precursors for TiC synthesis. Synthesis was executed during the process of mechanical alloying to form the composite granules. An investigation showed that the developed material was composed of a metal matrix and titanium carbide nanoreinforcements with an average size of approximately 22–23 nm. No reaction occurred between the matrix and the reinforcing particles at temperatures up to 900 °C for copper and 750 °C for aluminum. The developed aluminum composite can be applied as a master alloy for casting technologies.
•Method of in situ synthesis of TiC nanoparticles inside metal matrix is developed.•Nanodiamonds and titanium powders were precursors for the TiC nanoparticles synthesis.•In situ synthesis was executed by mechanical alloying.•Average TiC nanoparticles size in aluminum matrix equals 22–23 nm.•Developed composite with aluminum matrix can be used as “master alloy” for casting technology.
Thermodynamic calculations, scanning electron microscopy, X-ray diffraction analysis, and differential scanning calorimetry have been used to study the phase composition of a Al–Zn–Mg–Cu–Zr alloy ...that is rich in copper, which was additionally alloyed with yttrium or erbium. There are (Al), T, Al
8
Cu
4
Y, and AlMgY phases of solidification origin in the AlZnMgCuZrY alloy. The erbium-bearing AlZnMgCuZrEr alloy contains three additional intermetallic phases in addition to the T phase: two intermetallic phases with a composition close to the Al
8
Cu
4
Er phase and one of the Al
3
Er composition. One of the Al
8
Cu
4
Er-phase particles contains approximately 2 wt % Fe. Aging at 150°C led to a greater increment in the hardness of the erbium alloy, while the hardness level achieved is the same for all alloys under study. Overaging at 210 and 250°C takes place significantly earlier in the alloy without yttrium and erbium additives, given the same level of hardening. Taking the fact into account that the kinetics of aging depend mainly on the (Al) composition, the differences in kinetics in the alloys with additions can be explained by dispersoids formed during homogenization before quenching and the solid solution depleted of the main elements (zinc, magnesium, and copper). The yield strength of the alloys with yttrium and erbium additives is insignificantly lower at high temperatures, which is likely due to the lower alloying of the aluminum matrix. However, these alloys are of a better technological effectiveness at casting.
The structure and properties of rolled Al–Zn–Mg–Cu–Zr–Y(Er) alloys doped with manganese and modified with titanium have been studied. According to the results of tensile testing in the deformed state ...after annealings at 120–150°C for 1 h, the AlZnMgCuMnTi and AlZnMgCuMnTiEr alloys show a high yield strength of 417–456 MPa with a small relative elongation of 2–5.2%. The presence of additional dispersion-forming elements, such as yttrium and erbium, increases the density of particles precipitated in the course of homogenization annealing due to increase in the recrystallization onset temperature and in the hardness of the rolled alloys. After 1 h annealing at 350°C, the AlZnMgCuMnTi alloy has a completely recrystallized structure, while the alloys doped with yttrium and erbium only start to recrystallize. After quenching from the heated state at 465°C and aging at 120°C, the test alloys have a yield strength of more than 410 MPa, a tensile strength of more than 520 MPa, and an elongation of more than 10%. The obtained parameters are higher than the parameters of clad sheets of the high-strength heat-hardened Al–Zn–Mg–Cu (B95A) alloy and rods of the AlZn
4.5
Mg
1.5
Mn and AlZnMg
1.5
Mn alloys, and are comparable to the characteristic levels of rods of the Al–Zn–Mg–Cu (B95) alloy.
—
The structure and the properties of the cast Al–5Si–1.3Cu–0.5Mg–0.15Zr–0.15Y alloy have been investigated after the quenching and aging of the alloy ingot and deformed sheet. The introduction of ...zirconium and yttrium additives slightly modifies and increases the uniformity of the grain structure of the cast alloy. The Al
8
Cu
4
Y and Al
11
Cu
2
Y
2
Si
2
phase particles, which formed during solidification, do not change their morphology and do not dissolve upon homogenization. The yield strength of the alloy is 30–40 MPa higher than that of the alloy without additives, both at room temperature and 200°C because of the smaller grain size and solidification-induced phases. The yield strength in the alloy when quenched after rolling and aged is 289–296 MPa; the tensile strength is 374–387 MPa and the relative elongation is 13.5–15.5%. To enhance the service characteristics, especially at elevated temperatures, the alloying of silumins with low-cost yttrium in combination with zirconium offers an advantage over alloying with erbium.
The effect of small additions of erbium and zirconium on the microstructure, phase composition, kinetics of hardening during aging and softening during annealing after rolling of the ...Al–5Si–1.3Cu–0.5Mg alloy has been studied in this work. Erbium and zirconium form a phase of crystallization origin with aluminum, silicon, copper, and magnesium, which does not dissolve and does not change its morphology in the process of homogenization before quenching. Erbium and zirconium increase the aging effect after quenching, especially at 210°C, increase the yield stress at elevated temperatures, reduce the tendency to soften during annealing after rolling, and reduce the recrystallized grain size due to dispersoids formed during homogenization. Quenching of deformed sheets with subsequent aging leads to the achievement of slightly lower yield strength than low temperature annealing after rolling. In this case, a significantly higher ultimate strength of 344–375 MPa and ductility of 11.0–14.7% are achieved. The alloy with small additions of zirconium and erbium has higher characteristics of both strength and plasticity.
We present the first direct search for lepton flavour violating muon decay mediated by a new light particle X,
μ
+
→
e
+
X
,
X
→
γ
γ
. This search uses a dataset resulting from
7.5
×
10
14
stopped ...muons collected by the MEG experiment at the Paul Scherrer Institut in the period 2009–2013. No significant excess is found in the mass region 20–45 MeV/c
2
for lifetimes below 40 ps, and we set the most stringent branching ratio upper limits in the mass region of 20–40 MeV/c
2
, down to
O
(
10
-
11
)
at 90% confidence level.
The effect of scandium content on the structure and properties of alloy Al – 4.5% Zn – 4.5% Mg – 1% Cu – 0.12% Zr is determined. The microstructure of the alloy is studied with identification of the ...phases using an optical microscope and scanning and transmission electron microscopes. The Vickers hardness and the yield strength under heating are determined. The phase diagram is plotted and the nonequilibrium crystallization is described using the Thermo-Calc software and the TTAL5 database. It is shown that addition of 0.1% scandium contributes substantially enough into the growth of the hardness after 3-h annealing at 450°C and into the yield strength after 20-h aging at 175°C. The compositions studied are recommended as a base for designing new refractory alloys based on the Al – Zn – Mg – Cu system.
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