Hardness evolution of Al–Cr–N coatings under thermal load

2008 ◽  
Vol 23 (11) ◽  
pp. 2880-2885 ◽  
Author(s):  
Herbert Willmann ◽  
Paul H. Mayrhofer ◽  
Lars Hultman ◽  
Christian Mitterer
Keyword(s):  
Thermal Load ◽  
Structural Changes ◽  
Single Phase ◽  
Volume Fraction ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Al Content ◽  
Annealing Temperatures ◽  
Transmission Electron

Microstructure and hardness evolution of arc-evaporated single-phase cubic Al0.56Cr0.44N and Al0.68Cr0.32N coatings have been investigated after thermal treatment in Ar atmosphere. Based on a combination of differential scanning calorimetry and x-ray diffraction studies, we can conclude that Al0.56Cr0.44N undergoes only small structural changes without any decomposition for annealing temperatures Ta ⩽ 900 °C. Consequently, the hardness decreases only marginally from the as-deposited value of 30.0 ± 1.1 GPa to 29.4 ± 0.9 GPa with Ta increasing to 900 °C, respectively. The film with higher Al content (Al0.68Cr0.32N) exhibits formation of hexagonal (h) AlN at Ta ⩾ 700 °C, which occurs preferably at grain boundaries as identified by analytical transmission electron microscopy. Hence, the hardness increases from the as-deposited value of 30.1 ± 1.3 GPa to 31.6 ± 1.4 GPa with Ta = 725 °C. At higher temperatures, where the size and volume fraction of the h-AlN phase increases, the hardness decreases to 27.5 ± 1.0 GPa with Ta = 900 °C.

Preparation and Property of Al87Ce3Ni8.5Mn1.5 Nanophase Amorphous Composites

2011 ◽  
Vol 412 ◽  
pp. 263-266
Author(s):  
Hong Wei Zhang ◽  
Li Li Zhang ◽  
Feng Rui Zhai ◽  
Jia Jin Tian ◽  
Can Bang Zhang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Single Phase ◽  
Volume Fraction ◽  
Material Structure ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
Different Temperatures

The higher mechanical strength of Al87Ce3Ni8.5Mn1.5 nanophase amorphous composites has been obtained with two methods. The first nanophase amorphous composites are directly produced by the single roller spin quenching technology. The method taken for the second nanophase amorphous composites is at first to obtain amorphous single-phase alloy, followed by annealed at different temperatures .The formative condition, the microstructure, the particle size, the volume fraction of α-Al phase and microhardness of nanophase amorphous composites etc have been investigated and compared by X-ray diffraction (XRD) and transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The microstructure of composites produced by the second method is higher than the former, the fabricated material structure of the system is more uniform and the process is easier to control.

Structural and Electronic Properties of Zr-Ti-Cu-Ni-Be Alloys

2000 ◽  
Vol 644 ◽  
Author(s):  
Jörg F. Löffler ◽  
X.-P. Tang ◽  
Yue Wu ◽  
William L. Johnsona
Keyword(s):  
Differential Scanning Calorimetry ◽  
Small Angle Neutron Scattering ◽  
Crystallization Behavior ◽  
Volume Fraction ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Annealing Temperatures ◽  
Composition Space ◽  
Structural And Electronic Properties

AbstractWe present crystallization studies on Zr41.2Ti13.8Cu12.5Ni10Be22.5 (Vit1) and on other alloys, where the (Zr,Ti) and (Cu,Be) contents, along the line in composition space connecting Vit1 and Zr46.8Ti8.2Cu7.5Ni10Be27.5 (Vit4), were varied. Results from x-ray diffraction (XRD), small-angle neutron scattering (SANS) and differential scanning calorimetry (DSC) are combined to describe the crystallization behavior of these alloys at deep undercooling. SANS gives evidence for decomposition and the formation of nanometer sized crystals below a critical temperature Tc, which varies drastically as a function of composition. When Tc intersects with the glass transition temperature Tg, changes in the crystallization behavior are observed by DSC and XRD. At annealing temperatures near Tg, XRD resolves quasicrystalline phases for all alloy compositions from Vit1 to Vit4. From 9Be nuclear magnetic resonance (NMR) experiments performed on Vit1 upon annealing, we obtain information about the electronic structure and volume fraction of Be containing crystalline and quasicrystalline phases.

Origins of stored enthalpy in cryomilled nanocrystalline Zn

2001 ◽  
Vol 16 (12) ◽  
pp. 3485-3495 ◽  
Author(s):  
Xinghang Zhang ◽  
Haiyan Wang ◽  
Magdy Kassem ◽  
Jagdish Narayan ◽  
Carl C. Koch
Keyword(s):  
Structural Changes ◽  
Milling Time ◽  
Lattice Strain ◽  
Liquid Nitrogen Temperature ◽  
Temperature Differential ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
Mechanical Attrition

Nanocrystalline Zn was prepared by cryomilling (mechanical attrition at liquid nitrogen temperature). Differential scanning calorimetry (DSC), x-ray diffraction, and transmission electron microscopy were used to study the structural changes and grain size distribution with milling time and subsequent annealing. Maxima in both stored enthalpy (for the low-temperature DSC peak) and lattice strain on the Zn basal planes were observed at the same milling time. Dislocation density on the basal planes is proposed as a major source for lattice strain and the measured stored enthalpy. The released enthalpy that might be due to grain growth is very small.

scholarly journals Effects of Sintering Temperature on Densification, Microstructure and Mechanical Properties of Al-Based Alloy by High-Velocity Compaction

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 218
Author(s):  
Xianjie Yuan ◽  
Xuanhui Qu ◽  
Haiqing Yin ◽  
Zaiqiang Feng ◽  
Mingqi Tang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Velocity ◽  
Sintered Density ◽  
Sintering Temperature ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
High Velocity Compaction ◽  
Sintered Temperature

This present work investigates the effects of sintering temperature on densification, mechanical properties and microstructure of Al-based alloy pressed by high-velocity compaction. The green samples were heated under the flow of high pure (99.99 wt%) N2. The heating rate was 4 °C/min before 315 °C. For reducing the residual stress, the samples were isothermally held for one h. Then, the specimens were respectively heated at the rate of 10 °C/min to the temperature between 540 °C and 700 °C, held for one h, and then furnace-cooled to the room temperature. Results indicate that when the sintered temperature was 640 °C, both the sintered density and mechanical properties was optimum. Differential Scanning Calorimetry, X-ray diffraction of sintered samples, Scanning Electron Microscopy, Energy Dispersive Spectroscopy, and Transmission Electron Microscope were used to analyse the microstructure and phases.

Structural changes in titanium dioxide nanocrystals during plastic deformation

2005 ◽  
Vol 38 (5) ◽  
pp. 749-756 ◽  
Author(s):  
Ulrich Gesenhues
Keyword(s):  
Structural Changes ◽  
Crystal Size ◽  
Lower Layer ◽  
High Energy ◽  
Primary Crystal ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Hall Method ◽  
Means Of Transmission

The polygonization of 200 nm rutile crystals during dry ball-milling at 10gwas monitored in detail by means of transmission electron microscopy (TEM) and X-ray diffraction (XRD). The TEM results showed how to modify the Williamson–Hall method for a successful evaluation of crystal size and microstrain from XRD profiles. Macrostrain development was determined from the minute shift of the most intense reflection. In addition, changes in pycnometrical density were monitored. Accordingly, the primary crystal is disintegrated during milling into a mosaic of 12–35 nm pieces where the grain boundaries induce up to 1.2% microstrain in a lower layer of 6 nm thickness. Macrostrain in the interior of the crystals rises to 0.03%. The pycnometrical density, reflecting the packing density of atoms in the grain boundary, decreases steadily by 1.1%. The results bear relevance to our understanding of plastic flow and the mechanism of phase transitions of metal oxides during high-energy milling.

scholarly journals Structural Evolution in Wet Mechanically Alloyed Co-Fe-(Ta,W)-B Alloys

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 800
Author(s):  
Vladimír Girman ◽  
Maksym Lisnichuk ◽  
Daria Yudina ◽  
Miloš Matvija ◽  
Pavol Sovák ◽  
...  
Keyword(s):  
Structural Changes ◽  
Magnetic Measurements ◽  
Structural Evolution ◽  
High Energy ◽  
Control Agent ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
X Ray ◽  
Transmission Electron ◽  
X Ray Absorption

In the present study, the effect of wet mechanical alloying (MA) on the glass-forming ability (GFA) of Co43Fe20X5.5B31.5 (X = Ta, W) alloys was studied. The structural evolution during MA was investigated using high-energy X-ray diffraction, X-ray absorption spectroscopy, high-resolution transmission electron microscopy and magnetic measurements. Pair distribution function and extended X-ray absorption fine structure spectroscopy were used to characterize local atomic structure at various stages of MA. Besides structural changes, the magnetic properties of both compositions were investigated employing a vibrating sample magnetometer and thermomagnetic measurements. It was shown that using hexane as a process control agent during wet MA resulted in the formation of fully amorphous Co-Fe-Ta-B powder material at a shorter milling time (100 h) as compared to dry MA. It has also been shown that substituting Ta with W effectively suppresses GFA. After 100 h of MA of Co-Fe-W-B mixture, a nanocomposite material consisting of amorphous and nanocrystalline bcc-W phase was synthesized.

Size dependent behavior of Fe3O4crystals during electrochemical (de)lithiation: an in situ X-ray diffraction, ex situ X-ray absorption spectroscopy, transmission electron microscopy and theoretical investigation

2017 ◽  
Vol 19 (31) ◽  
pp. 20867-20880 ◽  
Author(s):  
David C. Bock ◽  
Christopher J. Pelliccione ◽  
Wei Zhang ◽  
Janis Timoshenko ◽  
K. W. Knehr ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Structural Changes ◽  
Ex Situ ◽  
X Ray Diffraction ◽  
X Ray ◽  
Size Dependent ◽  
Transmission Electron ◽  
Dependent Behavior ◽  
X Ray Absorption

Crystal and atomic structural changes of Fe3O4upon electrochemical (de)lithiation were determined.

Microstructures of two-phase Ti–Cr alloys containing the TiCr2 Laves phase intermetallic

1997 ◽  
Vol 12 (6) ◽  
pp. 1472-1480 ◽  
Author(s):  
Katherine C. Chen ◽  
Samuel M. Allen ◽  
James D. Livingston
Keyword(s):  
Laves Phase ◽  
X Ray Diffraction ◽  
Orientation Relationships ◽  
Phase Growth ◽  
Two Phase ◽  
X Ray ◽  
Lattice Constants ◽  
Annealing Temperatures ◽  
Transmission Electron ◽  
Phase Intermetallic

Microstructures of two-phase Ti–Cr alloys (Ti-rich bcc + TiCr2 and Cr-rich bcc + TiCr2) are analyzed. A variety of TiCr2 precipitate morphologies is encountered with different nominal alloy compositions and annealing temperatures. Lattice constants and crystal structures are determined by x-ray diffraction (XRD) and transmission electron microscopy (TEM). Orientation relationships between the beta bcc solid solution and C15 TiCr2 Laves phase are understood in terms of geometrical packing, and are consistent with a Laves phase growth mechanism involving twinning.

scholarly journals TEM Study of High-Temperature Precipitation of Delta Phase in Inconel 718 Alloy

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Moukrane Dehmas ◽  
Jacques Lacaze ◽  
Aliou Niang ◽  
Bernard Viguier
Keyword(s):  
Inconel 718 ◽  
Volume Fraction ◽  
Alloy 718 ◽  
Double Diffraction ◽  
X Ray Diffraction ◽  
Inconel 718 Alloy ◽  
X Ray ◽  
Delta Phase ◽  
Transmission Electron ◽  
Matrix Free

Inconel 718 is widely used because of its ability to retain strength at up to 650∘C for long periods of time through coherent metastable Ni3Nb precipitation associated with a smaller volume fraction of Ni3Al precipitates. At very long ageing times at service temperature, decomposes to the stable Ni3Nb phase. This latter phase is also present above the solvus and is used for grain control during forging of alloy 718. While most works available on precipitation have been performed at temperatures below the solvus, it appeared of interest to also investigate the case where phase precipitates directly from the fcc matrix free of precipitates. This was studied by X-ray diffraction and transmission electron microscopy (TEM). TEM observations confirmed the presence of rotation-ordered domains in plates, and some unexpected contrast could be explained by double diffraction due to overlapping phases.

Characterization of the Phase Transformations in the Shape Memory Alloy Ni-36 at.% Al

1991 ◽  
Vol 246 ◽  
Author(s):  
J.A. Horton ◽  
E.P. George ◽  
C.J. Sparks ◽  
M.Y. Kao ◽  
O.B. Cavin ◽  
...  
Keyword(s):  
High Temperature ◽  
Shape Memory ◽  
Phase Transformations ◽  
Hot Extrusion ◽  
Exothermic Peak ◽  
Nickel Aluminum ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron

AbstractA survey by differential scanning calorimetry (DSC) and recovery during heating of indentations on a series of nickel-aluminum alloys showed that the Ni-36 at.% Al composition has the best potential for a recoverable shape memory effect at temperatures above 100°C. The phase transformations were studied by high temperature transmission electron microscopy (TEM) and by high temperature x-ray diffraction (HTXRD). Quenching from 1200°C resulted in a single phase, fully martensitic structure. The initial quenched-in martensites were found by both TEM and X-ray diffraction to consist of primarily a body centered tetragonal (bct) phase with some body centered orthorhombic (bco) phase present. On the first heating cycle, DSC showed an endothermic peak at 121°C and an exothermic peak at 289°C, and upon cooling a martensite exothermic peak at 115° C. Upon subsequent cycles the 289°C peak disappeared. High temperature X-ray diffraction, with a heating rate of 2°C/min, showed the expected transformation of bct phase to B2 between 100 and 200°C, however the bco phase remained intact. At 400 to 450°C the B2 phase transformed to Ni2Al and Ni5Al3. During TEM heating experiments a dislocation-free martensite transformed reversibly to B2 at temperatures less than 150°C. At higher temperatures (nearly 600°C) 1/3, 1/3, 1/3 reflections from an ω-like phase formed. Upon cooling, the 1/3, 1/3, 1/3 reflections disappeared and a more complicated martensite resulted. Boron additions suppressed intergranular fracture and, as expected, resulted in no ductility improvements. Boron additions and/or hot extrusion encouraged the formation of a superordered bct structure with 1/2, 1/2, 0 reflections.

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