Microstructure in Rapidly Quenched Al-Ti,Al-B and Al-Ti-B Alloys

1986 ◽  
Vol 80 ◽  
Author(s):  
A. Majumdar ◽  
R. H. Mair ◽  
B. C. Muddle
Keyword(s):  
Heat Treatment ◽  
Solid Solution ◽  
Melt Spinning ◽  
Analytical Electron Microscopy ◽  
Primary Phase ◽  
Nucleation Sites ◽  
Uniform Dispersion ◽  
Average Grain Size ◽  
Melt Spun ◽  
Chill Cast

AbstractRapidly quenched ribbons (˜50m thickness) of Al-5wt.%Ti, Al-lwt.%B and a range of Al-Ti-B alloys have been produced by melt spinning under He atmosphere and the microstructures of the ribbons, following solidification and post-solidification heat treatment, characterized using analytical electron microscopy. In the Al-5Ti alloy, the coarse equilibrium primary phase (b.c.t. Al3 Ti) that is observed following conventional casting is replaced by fine (0.1–0. 2μm), cuboidal particles of a metastable cubic (Ll2) Al3Ti in melt-spun ribbon. These metastable particles form directly from the melt and act as nucleation sites for the solid solution which subsequently forms. A refined microstructure with an average grain size of 1–2μm results. A supersaturation of Ti is retained in matrix solid solution following solidification and a variety of solid state precipitate forms, including fine dispersions of coherent, metastable Al3 Ti particles, is observed to emerge during post-solidification heat treatment. For the Al-1B alloy, the coarse distribution of primary AlB2 particles in a chill-cast ingot is replaced by a fine, uniform dispersion of the metastable boride, α-AlB12, in the melt-spun ribbon. Attempts to induce a refined boride dispersion in melt-spun Al-Ti-B alloys have proved largely unsuccessful.

Microstructure of Semi-Solid Extruded Copper Alloy after Heat Treatment

2019 ◽  
Vol 285 ◽  
pp. 146-152
Author(s):  
Nai Yong Li ◽  
Han Xiao ◽  
Chi Xiong ◽  
De Hong Lu ◽  
Rong Feng Zhou
Keyword(s):  
Heat Treatment ◽  
Heat Treatment Temperature ◽  
Copper Alloy ◽  
Treatment Time ◽  
Solid Phase ◽  
Treatment Temperature ◽  
Primary Phase ◽  
Holding Time ◽  
Average Grain Size ◽  
Semi Solid

The semi-solid extruded ZCuSn10P1 copper alloy were annealed at different temperatures and time. The influences of heat treatment temperature and holding time on the microstructure of semi-solid ZCuSn10P1 copper alloy were investigated. The results show that with the increase of heat treatment temperature, the morphology of the semi-solid microstructure was improved, the sharp angle around the primary phase α-Cu and the liquid droplets were reduced. With the increase of heat treatment time, the solid-liquid segregation of the semi-solid structure was improved. The average grain size of the solid phase increased with the increasing of the holding time. After heat treatment, the solid solubility of the primary phase α-Cu increased, and the Sn and P elements in the liquid phase continued to diffuse to the primary phase α-Cu. The microstructure of semi-solid copper alloy was the most uniform after heat treatment at 350°C for 120 min.

Rapidly solidified Al3Ti-base alloys containing Ni

1988 ◽  
Vol 3 (1) ◽  
pp. 1-7 ◽  
Author(s):  
S. C. Huang ◽  
E. L. Hall ◽  
M. F. X. Gigliotti
Keyword(s):  
Melt Spinning ◽  
Single Phase ◽  
Analytical Electron Microscopy ◽  
Primary Phase ◽  
Second Phase ◽  
Equilibrium Conditions ◽  
Second Phase Particles ◽  
Analytical Electron ◽  
Wheel Side ◽  
Rapidly Solidified

Two Ni-modified Al3Ti alloys (Al65Ni10Ti25 and Al62Ni8Ti30) were rapidly solidified by melt spinning. The resulting microstructure was studied using light microscopy and analytical electron microscopy. Significant variations in the microstructure and phases were observed between the two ribbons and through the thickness of each ribbon.A single-phase γ-TiAl structure was seen near the wheel side of the Al62Ni8Ti30 ribbon, having microcrystalline grains ∼ 100 nm in diameter. Second-phase particles of Λ-AlNiTi were found in the remaining regions of that ribbon as the structure became columnar due to reduced rates of cooling. The Al65Ni10Ti25 alloy exhibited a primary phase of π-Al6.5 NiTi2.5. A second phase of μ-Al2NiTi formed with morphology and distribution varying through thickness. Microchemistry measurements on the phases indicated substantial deviations (up to 14 at. %) from the stoichiometric compositions. Further, the π, γ, and μ are low-temperature phases that do not form by solidification under equilibrium conditions. The observation of these phases thus suggests significant undercoolings achieved during the melt-spinning processing of the present alloys. Both ribbons are brittle as spun.

The Microstructure of Melt-Spun Iron Neodymium Permanent Magnet Materials

1985 ◽  
Vol 43 ◽  
pp. 210-211
Author(s):  
R. C. Dickenson
Keyword(s):  
Heat Treatment ◽  
Magnetic Properties ◽  
Melt Spinning ◽  
Ion Milling ◽  
X Ray ◽  
Fine Grained ◽  
Cold Stage ◽  
Melt Spun ◽  
Fine Grained Structure ◽  
Permanent Magnet Materials

Rapidly-quenched iron rare-earth boron alloys, with appropriate heat treatment, exhibit commercially promising permanent magnetic properties. This paper will report the results of an AEM characterization undertaken to explain the origin of the magnetic properties of an iron-neodymium-boron alloy in terms of its microstructure. Ribbons of Fe76 Nd16 B8 were prepared by melt-spinning, and were subsequently annealed at 700°C for 6 minutes to promote growth of a fine-grained structure. Samples were prepared for AEM by ion-milling the ribbons on a cold stage and examined using a Philips 400T TEM/STEM equipped with an energy dispersive x-ray unit.Three different microstructures are commonly observed in these alloys, and several others have been found in isolated cases.

The Effect of Ge and Ti Additions on the Microstructures and Properties of Nb-18Si Based Alloys

2011 ◽  
Vol 1295 ◽  
Author(s):  
Zifu Li ◽  
Panos Tsakiropoulos
Keyword(s):  
Heat Treatment ◽  
Solid Solution ◽  
Oxidation Resistance ◽  
Cast Alloy ◽  
High Volume ◽  
Primary Phase ◽  
Oxidation Behaviour ◽  
Volume Fractions ◽  
Two Phases ◽  
Cast Microstructure

ABSTRACTThe effects of Ge and Ti additions on the microstructure, hardness and oxidation behaviour of the alloys Nb–18Si–5Ge (ZF1) and Nb–24Ti–18Si–5Ge (ZF3) were studied. The as cast microstructure of the alloy ZF1 consisted of Nbss (cI2), and βNb5Si3 (tI32) with the latter being the primary phase and the two phases forming high volume fractions of Nbss + βNb5Si3 eutectic. The Ge addition stabilised the βNb5Si3 (tI32), and destabilised the Nb3Si (tP32) and the Nbss + Nb3Si eutectic. After heat treatment at 1200 °C for 100 h the βNb5Si3 (tI32) was partially transformed to the αNb5Si3 (tI32), and equilibrium was reached after heat treatment at 1500 °C for 100 h. The phases present in the as cast alloy ZF3 were the Nbss (cI2), and the Nb3Si (tP32), βNb5Si3 (tI32) and Ti5Si3 (hP16) silicides, with the latter forming a eutectic with the solid solution. The same phases were present after heat treatment at 1200 °C for 100 h but only the Nbss, and the Nb3Si and Nb5Si3 silicides were present after 100 h at 1500 °C where TiO2 was also formed. The Ge addition increased the microhardness of the Nb5Si3. The synergy of Ti with Ge resulted in a strong hardening effect and a remarkable retention of the hardness of the alloy ZF3. The additions of Ge and Ti to the Nb-18Si alloy improved the oxidation resistance at 800 °C, but pest oxidation behaviour was not eliminated.

Amorphous - Nanocrystalline Melt Spun Al-Si-Ni Based Alloys Modified with Cu and Zr

2013 ◽  
Vol 58 (2) ◽  
pp. 419-423 ◽  
Author(s):  
A. Kukuła-Kurzyniec ◽  
J. Dutkiewicz ◽  
P. Ochin ◽  
L. Perrière ◽  
P. Dłuzewski ◽  
...  
Keyword(s):  
Solid Solution ◽  
Melt Spinning ◽  
Amorphous Matrix ◽  
Amorphous Structure ◽  
Glass Forming Ability ◽  
Dsc Studies ◽  
Glass Forming ◽  
Melt Spun ◽  
Spinning Process ◽  
The Mean

In the present paper glass forming ability and structure of Al-Si-Ni based alloys were investigated. Three alloys starting from the ternary Al78Si12Ni10 [alloy 1], Al75Si12Ni8Zr5 [alloy 2] and Al73Si5Ni7Cu8Zr7 [alloy 3] were subjected to melt spinning process. The mean thickness of the obtained ribbons amounted between 25 and 40 μm. XRD and DSC studies showed predominantly amorphous structure of the ribbons. STEM and HRTEM methods confirmed participation of crystalline phase identified mainly as Al solid solution with the grain size near 10 nm. The mean microhardness [0.1N] of the ribbons was measured for alloys 1 - 3 respectively: 457 HV, 369 HV and 536 HV. The high value of hardness can be related to the presence of α-Al dispersoids in the amorphous matrix.

The Effect of Heat Treatment on the Corrosion Behavior of Amorphous Mg–Ni–Nd Alloys

1999 ◽  
Vol 14 (4) ◽  
pp. 1638-1644 ◽  
Author(s):  
C. H. Kam ◽  
Y. Li ◽  
S. C. Ng ◽  
A. Wee ◽  
J. S. Pan ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Corrosion Behavior ◽  
Amorphous Matrix ◽  
Nacl Solution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Heat Treated ◽  
Uniform Dispersion ◽  
Melt Spun

The effect of heat treatment on the corrosion behavior of seven amorphous melt-spun Mg–Ni–Nd alloys containing 10–20 at.% Ni and 5–15 at.% Nd has been studied. Hydrogen evolution testing was used to determine the dissolution rate of the heat-treated specimens immersed in a 3% NaCl solution saturated with Mg(OH)2. The dissolution rates of the partially crystallized specimens were found to be lower than those of the untreated specimens, while the fully crystallized specimens exhibited marked deterioration of corrosion resistance. X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies on the heat-treated specimens revealed precipitation of Mg3Nd, Mg12Nd, and Mg2Ni phases during the crystallization. TEM results show that the partially crystallized structure consists of uniform dispersion of either Mg3Nd or Mg2Ni in the amorphous matrix. In contrast, multiple phases precipitate in the fully crystallized specimen.

scholarly journals Microstructures of a SiC–ZrC Ceramic Fiber Derived from a Polymeric Precursor

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2142 ◽  
Author(s):  
Min Ge ◽  
Xiaoxu Lv ◽  
Hao Zhang ◽  
Shouquan Yu ◽  
Zhenxi Lu ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Melt Spinning ◽  
Zirconium Carbide ◽  
Temperature Treatment ◽  
Free Carbon ◽  
Ceramic Fiber ◽  
High Temperature Treatment ◽  
Average Grain Size ◽  
Electron Beam Curing ◽  
20 Nm

Continuous ceramic fiber comprising silicon carbide–zirconium carbide (SiC–ZrC) binary phases was obtained through melt spinning, electron-beam curing and pyrolysis of a pre-ceramic precursor of polyzirconocenecarbosilanes (PZCS). After pyrolysis and heat treatment, ZrC particles with mean diameters of 15–20 nm were formed and homogeneously dispersed in a matrix of fine crystalline β-SiC with an average grain size of 6–10 nm. Concentration of Zr in the fiber varies from 14.88% to 17.45% by mass. Fibers consisting of near-stoichiometric ZrC and SiC with little free carbon can be obtained through pyrolysis decarbonization of the as-cured fiber in hydrogen from room temperature to 1000 °C, and subsequently heat treatment in argon up to 1600 °C for 1 h. High-temperature treatment of these amorphous inorganic fibers leads to crystallization of the binary phases of β-SiC and ZrC. The removal of free carbon under hydrogen results in more rapid growth of β-SiC and ZrC crystals, in which obvious aggregation of the dispersed ZrC particles among the continuous β-SiC matrix can be ascribed to a fast migration of Zr cation.

Characterization of Melt Spun Cu-Nb Ribbons

1994 ◽  
Vol 362 ◽  
Author(s):  
Mei Ling Henne ◽  
Fereshteh Ebrahimi
Keyword(s):  
Heat Treatment ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Melt Spinning ◽  
Heat Treatments ◽  
Spherical Particles ◽  
Large Particles ◽  
Melt Spun ◽  
Rapidly Solidified

AbstractMicrostructure of rapidly solidified Cu-5wt%Nb ribbons produced by melt spinning was investigated by SEM and TEM techniques. Two heat treatments were done: 960°C 1 hour and 900° 3 hours. The microstructures contained three different type particles: (a)large particles located at the grain boundary, (b)small spherical particles located within the grains and at the grain boundaries, and (c)fine precipitates formed upon heat treatment. The evolution of the microstructure is discussed with regard to the previously reported studies.

The Precipitation of Si in AlCuSi Thin Films

1973 ◽  
Vol 31 ◽  
pp. 34-35 ◽  
Author(s):  
R. M. Anderson
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Heat Treatment ◽  
Solid Solution ◽  
Integrated Circuit ◽  
Copper Film ◽  
Solution Concentration ◽  
X Ray ◽  
Silicon Thin Films ◽  
Before And After

Aluminum-copper-silicon thin films have been considered as an interconnection metallurgy for integrated circuit applications. Various schemes have been proposed to incorporate small percent-ages of silicon into films that typically contain two to five percent copper. We undertook a study of the total effect of silicon on the aluminum copper film as revealed by transmission electron microscopy, scanning electron microscopy, x-ray diffraction and ion microprobe techniques as a function of the various deposition methods.X-ray investigations noted a change in solid solution concentration as a function of Si content before and after heat-treatment. The amount of solid solution in the Al increased with heat-treatment for films with ≥2% silicon and decreased for films <2% silicon.

AEM investigation of ZrO2 solid solution formation in ZrO2/mullite composites

1984 ◽  
Vol 42 ◽  
pp. 408-409
Author(s):  
T. R. Dinger
Keyword(s):  
Solid Solution ◽  
Ion Beam ◽  
Analytical Electron Microscopy ◽  
Transformation Toughening ◽  
Solid Solution Formation ◽  
Solution Formation ◽  
Propagating Crack ◽  
Analytical Electron ◽  
Microcrack Toughening ◽  
Made In

Zirconia (ZrO2) is often added to ceramic compacts to increase their toughness. The mechanisms by which this toughness increase occurs are generally accepted to be those of transformation toughening and microcracking. The mechanism of transformation toughening is based on the presence of metastable tetragonal ZrO2 which transforms to the monoclinic allotrope when stressed by a propagating crack. The decrease in volume which accompanies this transformation effectively relieves the applied stress at the crack tip and toughens the material; microcrack toughening arises from the deflection of a propagating crack around sharply angular inclusions.These mechanisms, however, do not explain the toughness increases associated with the class of composites investigated here. Analytical electron microscopy (AEM) has been used to determine whether solid solution effects could be the cause of this increased toughness. Specimens of a mullite (3Al2O3·2SiO2) + 15 vol. % ZrO2 were prepared by the usual technique of mechanical thinning followed by ion beam milling. All observations were made in a Philips EM400 TEM/STEM microscope fitted with EDXS and EELS spectrometers.

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