Study of the Effects of Al, Ta, W Additions on the Microstructure and Properties of Mosi2 Base Alloys

1994 ◽  
Vol 364 ◽  
Author(s):  
A. Stergiou ◽  
P. Tsakiropoulos
Keyword(s):  
Room Temperature ◽  
Lamellar Microstructure ◽  
Rapid Quenching ◽  
Al Alloy ◽  
Phase Selection ◽  
Complete Solid Solubility ◽  
Wheel Side ◽  
Two Phases ◽  
Solidification Microstructures ◽  
Thermal Stability Of

AbstractSolidification microstructures and phase selection in ingots and melt-spun ribbons of MoSi2, MoSi2-W-Ta and MoSi2-Al alloys were studied. Rapid quenching from the melt refined the grain size of all alloys by two orders of magnitude compared to the ingots. Zone A microstructures were formed in the wheel side of all alloy ribbons. Addition of W and Ta and of Al suppressed the formation of Mo5Si3 in the ingots and ribbons. Tungsten exhibited complete solid solubility in MoSi2. In the ribbons the solubility of Ta in MoSi2 was extended to 2 at% in Zone A, and in the ingots and zone B of the ribbons hexagonal (C40) TaSi2 and tetragonal (C11b) MoSi2 structures were formed. A fine lamellar microstructure between the Cllb and C40 phases was formed at 1350°C after 48h. Addition of Al changed dramatically the solidification microstructure which consisted of two phases C40 Mo(Al0.5Si0.5)2 and C54 MoAl1.3Si0.7. In the ingots the room temperature hardness decreased with addition of W and Ta and of Al. Addition of Al increased the thermal stability of the MoSi2-Al alloy.

Crystalline to Amorphous Transformation of Fe3B By 1 MeV Electron Irradiation

1981 ◽  
Vol 7 ◽  
Author(s):  
A. Mogro-Campero ◽  
E.L. Hall ◽  
J.L. Walter ◽  
A.J. Ratkowski
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Electron Irradiation ◽  
Room Temperature ◽  
Ion Irradiation ◽  
Rapid Quenching ◽  
Al Alloy ◽  
Bright Field ◽  
Transmission Electron ◽  
Diffraction Patterns

ABSTRACTSpecimens of amorphous Fe75B25 produced by rapid quenching from the melt were annealed to complete crystallization and subjected to 1 MeV electron irradiation in a transmission electron microscope at room temperature and at 130 K. The irradiation was interrupted at various intervals in order to obtain bright field images and diffraction patterns. The Fe3B crystals did not become amorphous at room temperature, even after damage levels of several dpa, whereas at 130 K the crystalline to amorphous transformation was observed to be complete at damage levels below 1 dpa. The results are combined with those of ion irradiation work on Fe3B; qualitative agreement is found between Fe3B and previous work on the Zr3Al alloy concerning their response to displacement damage by electron and ion irradiation.

On the Thermal Stability of ECAP Deformed FCC Metals

2007 ◽  
Vol 558-559 ◽  
pp. 259-264 ◽  
Author(s):  
Xenia Molodova ◽  
Günter Gottstein ◽  
Ralph Jörg Hellmig
Keyword(s):  
Thermal Stability ◽  
Microstructure Evolution ◽  
Room Temperature ◽  
Al Alloy ◽  
Rolled Material ◽  
Fcc Metals ◽  
Angular Pressing ◽  
Cold Rolled ◽  
Pure Cu ◽  
Thermal Stability Of

Pure Cu, CuZr and an Al-alloy were processed by Equal Channel Angular Pressing (ECAP) at room temperature applying route Bc. Microstructure evolution during ECAP and subsequent annealing was investigated. The deformed and annealed states were characterized by EBSD, TEM and microhardness tests. The microstructure variation was recorded and compared to the behavior of conventional cold rolled material. The study revealed a very low thermal stability of ECAP deformed pure Cu samples compared to cold rolled material with same total strain. However, the thermal stability was significantly improved by alloying with Zr. In contrast, ECAP deformed Al-alloy showed higher thermal stability than cold rolled material.

The Microstructure of Nb3Al-Mo Intermetallics

1994 ◽  
Vol 364 ◽  
Author(s):  
E. Passa ◽  
P. Tsakiropoulos
Keyword(s):  
Solid Solution ◽  
Grain Size ◽  
Room Temperature ◽  
Rapid Quenching ◽  
Ternary Alloys ◽  
Complete Solid Solubility ◽  
Melt Spun ◽  
B2 Phase ◽  
Melt Spun Ribbons ◽  
A15 Phase

AbstractThe microstructure of arc melted ingots and melt-spun ribbons of Nb-18A1, Nb-18Al-(20–40) Mo (at%) were studied. Rapid quenching from the melt refined the grain size by at least two orders of magnitude. In the binary alloy ingots and ribbons the Nb3Al (A15) and B2 phases were present. Molybdenum exhibited complete solid solubility in the bcc Nb-Al solid solution as well as in the Nb3Al (A15 phase). The former was the only phase present in the ribbons of the ternary alloys, while Nb3Al was detected only in the ingots. B2 phase was formed in the alloy with 20 at% Mo and the A2 phase was present in the alloy with 40 at% Mo. Furthermore, Mo addition increased the room temperature microhardness of the Nb-Al solid solution by ≈7 Kgmm−2/ at%Mo.

Thermal Breakdown Kinetics of 1-Ethyl-3-Methylimidazolium Ethylsulfate Measured Using Quantitative Infrared Spectroscopy

2017 ◽  
Vol 71 (12) ◽  
pp. 2626-2631 ◽  
Author(s):  
Jeffrey L. Wheeler ◽  
McKinley Pugh ◽  
S. Jake Atkins ◽  
Jason M. Porter
Keyword(s):  
Thermal Stability ◽  
Room Temperature ◽  
Computational Models ◽  
Elevated Temperatures ◽  
Molar Absorptivity ◽  
Ir Absorption ◽  
Optical Cell ◽  
Multiple Samples ◽  
Kinetics Of ◽  
Thermal Stability Of

In this work, the thermal stability of the room temperature ionic liquid (RTIL) 1-ethyl-3-methylimidazolium ethylsulfate ([EMIM][EtSO4]) is investigated using infrared (IR) spectroscopy. Quantitative IR absorption spectral data are measured for heated [EMIM][EtSO4]. Spectra have been collected between 25 ℃ and 100 ℃ using a heated optical cell. Multiple samples and cell pathlengths are used to determine quantitative values for the molar absorptivity of [EMIM][EtSO4]. These results are compared to previous computational models of the ion pair. These quantitative spectra are used to measure the rate of thermal decomposition of [EMIM][EtSO4] at elevated temperatures. The spectroscopic measurements of the rate of decomposition show that thermogravimetric methods overestimate the thermal stability of [EMIM][EtSO4].

Enhanced Thermal Stability of Esterified Lignin in Different Solvent Mediums

2018 ◽  
Vol 9 (1) ◽  
pp. 39-49 ◽  
Author(s):  
Sharifah Nurul Ain Syed Hashim ◽  
Sarani Zakaria ◽  
Chin Hua Chia ◽  
Sharifah Nabihah Syed Jaafar
Keyword(s):  
Thermal Stability ◽  
Alkaline Solution ◽  
Room Temperature ◽  
Hydroxyl Groups ◽  
Aqueous Alkaline Solution ◽  
Alkali Lignin ◽  
Weight Percentage ◽  
H Nmr ◽  
Ft Ir ◽  
Thermal Stability Of

In this study, soda alkali lignin from oil palm empty fruit bunch (EFB-AL) and kenaf core (KC-AL) are esterified with maleic anhydride under two different conditions, namely i) pyridine at temperature of 120°C for 3h and ii) aqueous alkaline solution at room temperature for 4h. As a result, the weight percentage gain (WPG) of the esterified EFB-AL (EFB-EL) and esterified KC-AL (KC-EL) in pyridine demonstrated a higher compared to aqueous alkaline solution. The FT-IR results of EFB-EL and KC-EL in both solvents exhibited some changes at the carbonyl and hydroxyl groups. Furthermore, the esterification process induced the carboxylic peak to appear in both alkali lignin samples. The outcome is confirmed by conducting H-NMR analysis, which demonstrated ester and carboxylic acid peaks within the spectral analysis. Finally, the TGA results showed both EFB-EL and KC-EL that are exposed to aqueous alkaline actually possessed better thermal stability and higher activation energy (Ea) compared to the esterified samples in pyridine.

The Structure and Properties of Boundaries in Bicrystals of Boron-Doped Ni3(Al,l at% Ta)

1990 ◽  
Vol 213 ◽  
Author(s):  
M. J. Mills ◽  
S. H. Goods ◽  
S. M. Foiles
Keyword(s):  
Room Temperature ◽  
Tensile Ductility ◽  
Al Alloy ◽  
Boron Doped ◽  
Transmission Electron ◽  
Temperature Heat ◽  
Atomistic Calculations ◽  
Rate Of Cooling ◽  
Temperature Heat Treatment ◽  
Ductile State

ABSTRACTThe effect of boron on the structure and macroscopic properties of an isolated grain boundary in bicrystals of a non-stoichiometric Ni3Al alloy (76 at% Ni, 23 at% Al, 1 at%Ta) has been studied. The room temperature tensile ductility and fracture mode of the bicrystals varies dramatically with the rate of cooling after elevated temperature heat treatment. In the absence of significant segregation of boron to the boundary, the bicrystals fail via brittle interfacial fracture with little or no ductility. When the segregation of boron to the boundary is maximized, the bicrystals are highly ductile. High resolution transmission electron microscopy reveals that this ductile state is achieved without the formation of a detectable region of compositional disorder at the boundary. Atomistic calculations using a Monte Carlo scheme predict that only partial disordering of the planes immediately adjacent to the boundary should occur for Ni-rich alloys both with and without boron. These results suggest that the presence of boron causes an increase in the cohesive energy of the boundaries rather than a change in the local compositional ordering.

STRUCTURE AND MAGNETIC PROPERTIES OF MECHANICAL ALLOYED Mn-15at.%Al

2013 ◽  
Vol 12 (01) ◽  
pp. 1350006
Author(s):  
AHMED E. HANNORA ◽  
FARIED F. HANNA ◽  
LOTFY K. MAREI
Keyword(s):  
Thermal Analysis ◽  
Room Temperature ◽  
Average Crystallite Size ◽  
Al Alloy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Milled Sample ◽  
Powder Samples ◽  
Xrd Patterns ◽  
Method Analysis

Mechanical alloying (MA) method has been used to produce nanocrystallite Mn -15at.% Al alloy. X-ray diffraction (XRD) patterns for the as-milled elemental α- Mn and aluminum powder samples show a mixture of α + β- MnAl phases after 20 h of milling and changes to a dominant β- MnAl phase structure after 50 h. An average crystallite size of 40 nm was determined from Hall–Williamson method analysis after 5 h of milling. Moreover, the thermal analysis results using differential thermal analysis (DTA), suggested a possible phase transformation after 20 h of milling. Isothermal treatments are carried in the temperature range of 450°C to 1000°C. Room-temperature vibrating sample magnetometer (VSM) measurements of the hysteretic response revealed that the saturation magnetization Bs and coercivity Hc for 10 h ball milled sample are ~ 2.1 emu/g and ~ 92 Oe, respectively.

Creep behaviour and thermal stability of cryomilled Al alloy

2005 ◽  
Vol 85 (2) ◽  
pp. 97-108 ◽  
Author(s):  
B. Q. Han * ◽  
Z. Zhang ◽  
E. J. Lavernia
Keyword(s):  
Thermal Stability ◽  
Creep Behaviour ◽  
Al Alloy ◽  
Thermal Stability Of

Thermal Stability of Magnetic Properties in Dehydrogenated Triarylmethane Resins

1989 ◽  
Vol 173 ◽  
Author(s):  
Michiya Otani ◽  
Sugio Otani
Keyword(s):  
Thermal Stability ◽  
Magnetic Properties ◽  
Magnetic Property ◽  
Room Temperature ◽  
Permanent Magnets ◽  
Elevated Temperatures ◽  
Mechanical Response ◽  
The Stability ◽  
Thermal Stability Of

ABSTRACTThe stability of the magnetic properties of dehydrogenated triaryl-methane resins was investigated both at room temperature and at elevated temperatures. A magnetic property different from that reported in a previous paper was found in the course of studying the reproducibility of synthesis. This new property was examined through a mechanical response of the resins to a set of permanent magnets.

Sign in / Sign up

Export Citation Format

Share Document