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•Cu architectures with dense microstructure and well-defined complex geometries are achievable through L-PBF with green laser.•Cu lattice structures exhibit continuous plastic ...deformation with strain hardening under compression.•Cu lattice structures show a significant increase in strengths at a dynamic strain rate of ∼ 1000/s.•Cu lattice structures exhibit a high energy absorption capacity of 128 J/mm3.
Additive manufacturing of pure copper (Cu) via laser-powder bed fusion (L-PBF) is challenging due to the low energy absorptivity under infra-red laser. As a result, 3-dimensional architectures, known for excellent load-bearing and energy absorption capabilities, have not been fabricated in pure Cu, so far. This study, for the first time, Cu lattice structures are fabricated through laser-powder bed fusion (L-PBF) with green laser (λ = 515 nm). Structural and microstructural analysis confirm that the lattice structures consist of well-defined unit-cells and show dense microstructure. The deformation behavior is investigated under a wide range of strain rates from ∼0.001 /s to ∼1000 /s. The stress–strain curves exhibit a smooth and continuous deformation without any post-yield softening, which can be attributed to the intrinsic mechanical properties of Cu. Correlated with post-mortem microscopy examination, the rate-dependent deformation behavior of pure Cu lattice structures is investigated and rationalized. The current work suggests that the complex Cu architectures can be fabricated by L-PBF with green laser and are suitable for dynamic loading applications.
A new mineral rossovskyite named after L.N. Rossovsky was discovered in granite pegmatites of the Bulgut occurrence, Altai Mts., Western Mongolia. Associated minerals are microcline, muscovite, ...quartz, albite, garnet of the almandine–spessartine series, beryl, apatite, triplite, zircon, pyrite, yttrobetafite-(Y) and schorl. Rossovskyite forms flattened anhedral grains up to 6 × 6 × 2 cm. The color of the mineral is black, and the streak is black as well. The luster is semi-metallic, dull. Mohs hardness is 6. No cleavage or parting is observed. Rossovskyite is brittle, with uneven fracture. The density measured by the hydrostatic weighing method is 6.06 g/cm
2
, and the density calculated from the empirical formula is 6.302 g/cm
3
. Rossovskyite is biaxial, and the color in reflection is gray to dark gray. The IR spectrum contains strong band at 567 cm
−1
(with shoulders at 500 and 600 cm
−1
) corresponding to cation–oxygen stretching vibrations and weak bands at 1093 and 1185 cm
−1
assigned as overtones. The reflection spectrum in visible range is obtained. According to the Mössbauer spectrum, the ratio Fe
2+
:Fe
3+
is 35.6:64.4. The chemical composition is as follows (electron microprobe, Fe apportioned between FeO and Fe
2
O
3
based on Mössbauer data, wt%): MnO 1.68, FeO 5.92, Fe
2
O
3
14.66, TiO
2
7.69, Nb
2
O
5
26.59, Ta
2
O
5
37.51, WO
3
5.61, total 99.66. The empirical formula calculated on four O atoms is:
Mn
0.06
2
+
Fe
0.21
2
+
Fe
0.47
3
+
Ti
0.25
Nb
0.51
Ta
0.43
W
0.06
O
4
. The crystal structure was determined using single-crystal X-ray diffraction data. The new mineral is monoclinic, space group
P
2/
c
,
a
= 4.668(1),
b
= 5.659(1),
c
= 5.061(1) Å,
β
= 90.21(1)º;
V
= 133.70(4) Å
3
,
Z
= 2. Topologically, the structure of rossovskyite is analogous to that of wolframite-group minerals. The crystal-chemical formula of rossovskyite is (Fe
3+
, Fe
2+
, Mn)
0.57
Ta
0.32
Nb
0.11
Nb
0.40
Ti
0.25
Fe
0.18
Ta
0.11
W
0.06
O
4
. The strongest lines of the powder X-ray diffraction pattern
d,
Å (I, %) (
hkl
) are as follows: 3.604 (49) (110), 2.938 (100) (−1−11), 2.534 (23) (002), 2.476 (29) (021), 2.337 (27) (200), 1.718 (26) (−202), 1.698 (31) (−2−21), 1.440 (21) (−311). The type specimen of rossovskyite is deposited in the Mineralogical Museum of the Tomsk State University, Tomsk, 634050 Russia, with the inventory number 20927.
We report on the progress of the construction of the thermal time-of-flight spectrometer with polarization analysis TOPAS at the Mayer-Leibnitz Zentrum (MLZ). The instrument components approach the ...status to be ready for installation. The special feature of the instrument is its capability for wide-angle polarization analysis in the thermal spectral range. Here we describe a novel approach to rotate the neutron spin adiabatically into the X, Y or Z direction of the laboratory frame by combination of permanent magnets aligned as Halbach rings and electrically generated fields. Despite the severe spatial restrictions the design exhibits a very high adiabaticity and interacts only weakly with the coil layout for the analyzing 3He spin filter cell (SFC).
Vesuvianite containing 5.85 wt% TiO2 from an Alpine‐cleft‐type assemblage outcropped near Alchuri, Shigar Valley, Northern Areas, Pakistan, has been investigated by means of electron microprobe ...analyses, gas‐chromatographic analysis of H2O, X‐ray powder diffraction, single‐crystal X‐ray structure refinement, 27Al NMR, 57Fe Mössbauer spectroscopy, IR spectroscopy and optical measurements. Tetragonal unit‐cell parameters are: a = 15.5326 (2), c = 11.8040 (2) Å, space group P4/nnc. The structure was refined to final R1 = 0.031, wR2 = 0.057 for 11247 I > 2σ(I). A general crystal‐chemical formula of studied sample can be written as follows (Z = 2): 8–9(Ca17.1Na0.9) 8Ca1.05(Fe2+0.44Fe3+0.34Mg0.22) 6(Al3.59Mg0.41) 6(Al4.03Ti2.20Fe3+1.37Fe2+0.40) (Si18O68) (OH)5.84O2.83F1.33. The octahedral site Y2 is Al‐dominant and does not contain transition elements. Another octahedral site Y3 is also Al‐dominant and contains Fe2+, Fe3+ and Ti. The site Y1 is split into Y1a and Y1b predominantly occupied by Fe2+ and Fe3+, respectively. The role of the Y1 site in the diversity of vesuvianite‐group minerals is discussed.
Vesuvianite containing 5.85 wt% TiO2 from an Alpine‐cleft‐type assemblage outcropped near Alchuri, Shigar Valley, Northern Areas, Pakistan, has been studied. The role of the Y1 site in the diversity of vesuvianite‐group minerals is discussed.
Auriferous vein samples of the Angolan M'Popo deposit were characterized by a combination of 2D microscopy and 3D computed tomography (CT) in order to visualize and assess the gold distribution and ...gold morphology in in situ high-grade gold ore. The 0.1-2.4 m wide hydrothermal quartz veins in the Mesoproterozoic M'Popo granitic complex are composed mainly of quartz and pyrite, minor other sulfides and (visible) gold. The favourable X-ray attenuation/density contrast within this mineral assemblage allows delineation of the gold particle fraction so that gold particles of <0.01-19.95 mm³ in volume have been identified. Statistical analysis reveals that the bulk (∼99.98%) of all gold particles belong to the smallest volume classes (≤0.02 mm²) while large particles (>0.5 mm³) are few. The contrast between rounded, compact smaller particles and branched larger ones is clearly expressed in the CT reconstructions while transitions between these reflect a likely continuum in gold mineralization.
The neutron time-of-flight spectrometer NEAT has a long history of successful applications and is best suited to probe dynamic phenomena directly in the large time domain 10−14 – 10−10 s and on the ...length scale ranging from 0.05 to up to about 5 nm. To address user community needs for more powerful instrumental capabilities, a concept of the full upgrade of NEAT has been proposed. The upgrade started in 2010 after a rigorous internal and external selection process and resulted in 300-fold neutron count rate increase compared to NEAT′1995. Combined with new instrumental and sample environmental capabilities the upgrade allows NEAT to maintain itself at the best world class level and provide an outstanding experimental tool for a broad range of scientific applications. The advanced features of the new instrument include an integrated guide-chopper system that delivers neutrons with flexible beam properties: either highly homogeneous beam with low divergence suitable for single crystals studies or “hot-spot” neutron distribution serving best small samples. Substantial increase of the detector angle coverage is achieved by using 416 3He position sensitive detectors. Placed at 3 m from the sample, the detectors cover 20 m2 area and are equipped with modern electronics and DAQ using event recording techniques. The installation of hardware has been completed in June 2016 and on January 23, 2017 NEAT has welcomed its first regular users who took advantage of the high counting rate, broad available range of incoming neutron wavelengths and high flexibility of NEAT. Here we present details of NEAT upgrade, measured instrument characteristics and show first experimental results.
We report on the first results of the newly proposed and prototyped PASTIS coil set, enabling for XYZ polarization analysis on the future thermal time-of flight spectrometers. Our setup uses a ...wide-angle banana shaped 3He Neutron Spin Filter cell (NSF) to cover a large range of scattering solid angle. The design assures relative magnetic field gradients < 10-3 cm-1 and large solid angle areas not interrupted by either coils or supports. In the vertical direction nearly 40° are open and the blind spots in the horizontal scattering plane comprise only 3° in 180° due to the square X and Y compensation coils. We present the first results of the field mapping and relaxations time measurements using a large 3He SEOP polarized GE180 doughnut cell.
The neutron time-of-flight spectrometer NEAT has a long history of successful applications and is best suited to probe dynamic phenomena directly in the large time domain 10-14 – 10-10 s and on the ...length scale ranging from 0.05 to up to about 5 nm. To address user community needs for more powerful instrumental capabilities, a concept of the full upgrade of NEAT has been proposed. The upgrade started in 2010 after a rigorous internal and external selection process and resulted in 300-fold neutron count rate increase compared to NEAT'1995. Combined with new instrumental and sample environmental capabilities the upgrade allows NEAT to maintain itself at the best world class level and provide an outstanding experimental tool for a broad range of scientific applications. The advanced features of the new instrument include an integrated guide-chopper system that delivers neutrons with flexible beam properties: either highly homogeneous beam with low divergence suitable for single crystals studies or "hot-spot" neutron distribution serving best small samples. Substantial increase of the detector angle coverage is achieved by using 416 3He position sensitive detectors. Placed at 3 m from the sample, the detectors cover 20 m2 area and are equipped with modern electronics and DAQ using event recording techniques. The installation of hardware has been completed in June 2016 and on January 23, 2017 NEAT has welcomed its first regular users who took advantage of the high counting rate, broad available range of incoming neutron wavelengths and high flexibility of NEAT. Here we present details of NEAT upgrade, measured instrument characteristics and show first experimental results.
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