Synthesis of W-Y2O3 alloys by freeze-drying and subsequent low temperature sintering: Microstructure refinement and second phase particles regulation

2020 ◽  
Vol 36 ◽  
pp. 84-90 ◽  
Author(s):  
Weiqiang Hu ◽  
Zhi Dong ◽  
Liming Yu ◽  
Zongqing Ma ◽  
Yongchang Liu
Keyword(s):  
Low Temperature ◽  
Freeze Drying ◽  
Second Phase ◽  
Low Temperature Sintering ◽  
Microstructure Refinement ◽  
Second Phase Particles

The synthesis of TiC dispersed strengthened Mo alloy by freeze-drying technology and subsequent low temperature sintering

2021 ◽  
Vol 198 ◽  
pp. 113831 ◽  
Author(s):  
Weiqiang Hu ◽  
Zunfeng Du ◽  
Zhizhong Dong ◽  
Liming Yu ◽  
Tansir Ahamad ◽  
...  
Keyword(s):  
Low Temperature ◽  
Freeze Drying ◽  
Low Temperature Sintering ◽  
Drying Technology

Microstructure refinement in W–Y2O3 alloys via an improved hydrothermal synthesis method and low temperature sintering

2020 ◽  
Vol 7 (3) ◽  
pp. 659-666 ◽  
Author(s):  
Weiqiang Hu ◽  
Zhi Dong ◽  
Zongqing Ma ◽  
Yongchang Liu
Keyword(s):  
Hydrothermal Synthesis ◽  
Low Temperature ◽  
High Performance ◽  
Synthesis Method ◽  
Oxide Dispersion Strengthened ◽  
Polyvinyl Pyrrolidone ◽  
Oxide Dispersion ◽  
Low Temperature Sintering ◽  
Microstructure Refinement

In order to prepare high performance oxide-dispersion-strengthened tungsten-based alloys, W–Y2O3 composite nanopowders were prepared using an improved hydrothermal synthesis method with the addition of the surfactant polyvinyl pyrrolidone (PVP).

Polishing process effect on the image of dispersed precipitates

1984 ◽  
Vol 42 ◽  
pp. 534-535
Author(s):  
C.T. Hu ◽  
C.W. Allen
Keyword(s):  
Matrix Material ◽  
Specimen Preparation ◽  
Second Phase ◽  
Precipitate Particle ◽  
Polishing Process ◽  
Second Phase Particles ◽  
The Matrix ◽  
Surface Profiles ◽  
Thinning Process

One important problem in determination of precipitate particle size is the effect of preferential thinning during TEM specimen preparation. Figure 1a schematically represents the original polydispersed Ni3Al precipitates in the Ni rich matrix. The three possible type surface profiles of TEM specimens, which result after electrolytic thinning process are illustrated in Figure 1b. c. & d. These various surface profiles could be produced by using different polishing electrolytes and conditions (i.e. temperature and electric current). The matrix-preferential-etching process causes the matrix material to be attacked much more rapidly than the second phase particles. Figure 1b indicated the result. The nonpreferential and precipitate-preferential-etching results are shown in Figures 1c and 1d respectively.

A Comparison of Tem and Apfim to the Interpretation of Modulated Microstructures

1985 ◽  
Vol 43 ◽  
pp. 70-71
Author(s):  
M.G. Burke ◽  
M.K. Miller
Keyword(s):  
Low Temperature ◽  
Microstructural Characterization ◽  
Superlattice Reflection ◽  
High Volume ◽  
Atom Probe ◽  
Dark Field ◽  
Miscibility Gap ◽  
Second Phase ◽  
Two Phase ◽  
Probe Field

Interpretation of fine-scale microstructures containing high volume fractions of second phase is complex. In particular, microstructures developed through decomposition within low temperature miscibility gaps may be extremely fine. This paper compares the morphological interpretations of such complex microstructures by the high-resolution techniques of TEM and atom probe field-ion microscopy (APFIM).The Fe-25 at% Be alloy selected for this study was aged within the low temperature miscibility gap to form a <100> aligned two-phase microstructure. This triaxially modulated microstructure is composed of an Fe-rich ferrite phase and a B2-ordered Be-enriched phase. The microstructural characterization through conventional bright-field TEM is inadequate because of the many contributions to image contrast. The ordering reaction which accompanies spinodal decomposition in this alloy permits simplification of the image by the use of the centered dark field technique to image just one phase. A CDF image formed with a B2 superlattice reflection is shown in fig. 1. In this CDF micrograph, the the B2-ordered Be-enriched phase appears as bright regions in the darkly-imaging ferrite. By examining the specimen in a [001] orientation, the <100> nature of the modulations is evident.

Analytical Electron Microscopy Study of Second-Phase Particles in 7075 and 7475 Aluminum Alloys

1985 ◽  
Vol 43 ◽  
pp. 348-349
Author(s):  
M. Raghavan ◽  
J. Y. Koo ◽  
J. W. Steeds ◽  
B. K. Park
Keyword(s):  
Aluminum Alloys ◽  
Silicon Oxide ◽  
Analytical Electron Microscopy ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Partial Substitution ◽  
Second Phase ◽  
X Ray ◽  
Second Phase Particles ◽  
Almost All

X-ray microanalysis and Convergent Beam Electron Diffraction (CBD) studies were conducted to characterize the second phase particles in two commercial aluminum alloys -- 7075 and 7475. The second phase particles studied were large (approximately 2-5μm) constituent phases and relatively fine ( ∼ 0.05-1μn) dispersoid particles, Figures 1A and B. Based on the crystal structure and chemical composition analyses, the constituent phases found in these alloys were identified to be Al7Cu2Fe, (Al,Cu)6(Fe,Cu), α-Al12Fe3Si, Mg2Si, amorphous silicon oxide and the modified 6Fe compounds, in decreasing order of abundance. The results of quantitative X-ray microanalysis of all the constituent phases are listed in Table I. The data show that, in almost all the phases, partial substitution of alloying elements occurred resulting in small deviations from the published stoichiometric compositions of the binary and ternary compounds.

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