Selected Area Diffraction Pattern Analysis Research Articles

Crystallographic study of Ni2Ge phase in binary NiGe alloy system

The existence of Ni2Ge phase in a binary Ni-37.8 wt% Ge alloy has been determined by means of metallography, scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray analysis. The crystal structure of the phase is found to be primitive orthorhombic with lattice parameters of a = 0.51 nm, b = 0.383 nm and c = 0.726 nm. Its space group has been determined to be Pnma (No. 62), by the reflection condition analysis of selected-area diffraction patterns and zone-axis symmetry analysis of convergent-beam electron diffraction patterns. Twinning has been observed to occur in Ni2Ge phase. Its shear plane, twinning plane and twinning direction have been determined to be (100), (011) and [0–11], respectively, by the analysis of transformation matrix and lattice structure of the twins.

Microstructure characterization of Sm-Fe-Zr melt-spun hard magnetic systems

Several phases were identified in Sm/sub x/-Fe/sub 73/-Zr/sub 27-x/ melt-spun materials by transmission electron microscopy selected area diffraction pattern analysis. Aside from the PuNi/sub 3/-type phase common to materials with high and low Sm content, several other phases are thought to be present in the low coercivity system (x=14), such as Fe/sub 7/Sm and Fe/sub 3/Zr.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Quasicrystalline and related crystalline phases in a rapidly solidified 2024-2Li aluminium alloy

The formation and decomposition of quasicrystalline and crystalline phases in as-rapidly solidified and annealed commercial AISI 2024 aluminium alloy containing 2 wt% Li have been investigated by detailed transmission electron microscopy, including a combination of bright field and dark field imaging, selected area diffraction pattern analysis and energy dispersive X-ray microanalysis. The microstructure of as-melt spun 2024-2Li consists of α-Al cell, containing small coherent δ′ precipitates, and particles or a continuous network of the icosahedral phase at the cell boundaries. After annealing at 300°C, the intercellular particles of the icosahedral phase coarsen progressively and assume a more faceted shape; after annealing at 400°C, particles of the decagonal and crystalline O phases precipitate heterogeneously on preexisting particles of the icosahedral phase; and after annealing at 500°C, the icosahedral and decagonal phases dissolve completely, and small particles of the crystalline O phase remain together with newly precipitated plates of the T 1 phase. The icosahedral phase in melt spun and melt spun/annealed 2024-2Li belongs to the Al 6CuLi 3 class of icosahedral phases, with a quasilattice constant of 0.51 nm, a stoichiometry of (Al,Si) 6(Cu, Mn, Fe) (Li, Mg) 3 and an average composition of Al-24.1 at.% Cu-64 at.% Mg-1.7 at.% Si-0.3 at.% Mn-0.5 at.% Fe as melt spun and Al-21.9 at.% Cu-6.3 at.% Mg-1.0 at.% Si-0.5 at.% Fe as-heat-treated. The decagonal phase in melt spun/annealed 2024-2Li belongs to the Al 4Mn class of decagonal phases, with a periodicity of 1.23 nm along the 10-fold symmetry axis, a stoichoimetry of Al 3(Cu, Mn, Fe) and an average composition of Al-10.3 at.% Cu-13.8 at.% Mn-2.3 at.% Fe. The crystalline O phase in melt spun/annealed 2024-2Li has an orthorhombic structure with lattice parameters of a = 2.24 nm, b = 2.35 nm and c = 1.23 nm, a stoichiometry of Al 3(Cu, Mn, Fe), and an average composition of Al-11.0 at.% Cu-14.8 at.% Mn-3.9 at.% Fe. Detailed analysis of selected area diffraction patterns shows a close similarity between the icosahedral, decagonal and crystalline O phases in melt spun and melt spun/annealed 2024-2Li. In particular, the decagonal phase and crystalline O phases have a similar composition, and exhibit an orientation relationship which can be expressed as: • [D10]//[001] o • [D2 a]//[100] o • [D2 b]//[010] o suggesting that the orthorhombic O phase is an approximant structure for the decagonal phase.

Growth, structure and electrical characteristics of epitaxial nickel silicide from chemically electroless Ni deposition on Si

The epitaxial NiSi2 has been successfully grown on (100) and (111) silicon single crystals by chemical electroless deposition and isothermal annealing for the first time. Transmission electron microscopy (TEM) was applied to study the structure and orientation relationship of the films and substrates. The nickel silicide formed on both (100) and (111) Si substrates was identified to be NiSi2 and was found to have epitaxial relationship with the substrates by bright field imaging and selected area diffraction pattern analysiS. Square, hexagonal and irregular dislocation networks were observed. The orientation relationships of silicide phase with respect to (100)Si substrate were identified to be (220)Si ∥ (220)NiSi2, (400)Si ∥ (400)NiSi2 and (001) Si ∥ (001)NiSi2. The orientation relationships of silicide phase with respect to (111)Si substrate were identified to be (220)Si ∥ (02¯2)NiSi2, (3¯11) Si ∥ (31¯1) NiSi2 and [1¯1¯4]Si ∥ [1¯1¯2]NiSi2. The average spacing of interfacial dislocations was about 90 nm for epitaxial silicide formed on (100)Si at 800° C, which is narrower than that on (111)Si. These spacings decreased with increasing annealing temperature.