High Temperature Hardness of Bulk Single Crystal GaN

1999 ◽  
Vol 595 ◽  
Author(s):  
I. Yonenaga ◽  
T. Hoshi ◽  
A. Usui
Keyword(s):  
High Temperature ◽  
Single Crystal ◽  
Room Temperature ◽  
Applied Load ◽  
Elevated Temperatures ◽  
Mechanical Stability ◽  
Bulk Single Crystal ◽  
Indentation Method ◽  
First Time ◽  
High Mechanical Stability

AbstractThe hardness of single crystal GaN (gallium nitride) at elevated temperature is measured for the first time and compared with other materials. A Vickers indentation method was used to determine the hardness of crack-free GaN samples under an applied load of 0.5N in the temperature range 20 - 1200°C. The hardness is 10.8 GPa at room temperature, which is comparable to that of Si. At elevated temperatures GaN shows higher hardness than Si and GaAs. A high mechanical stability for GaN at high temperature is deduced.

scholarly journals High Temperature Hardness of Bulk Single Crystal GaN

2000 ◽  
Vol 5 (S1) ◽  
pp. 343-348
Author(s):  
I. Yonenaga ◽  
T. Hoshi ◽  
A. Usui
Keyword(s):  
High Temperature ◽  
Single Crystal ◽  
Room Temperature ◽  
Applied Load ◽  
Elevated Temperatures ◽  
Mechanical Stability ◽  
Bulk Single Crystal ◽  
Indentation Method ◽  
First Time ◽  
High Mechanical Stability

The hardness of single crystal GaN (gallium nitride) at elevated temperature is measured for the first time and compared with other materials. A Vickers indentation method was used to determine the hardness of crack-free GaN samples under an applied load of 0.5N in the temperature range 20 - 1200°C. The hardness is 10.8 GPa at room temperature, which is comparable to that of Si. At elevated temperatures GaN shows higher hardness than Si and GaAs. A high mechanical stability for GaN at high temperature is deduced.

High-Temperature Hardness of Bulk Single-Crystal AlN

2001 ◽  
Vol 693 ◽  
Author(s):  
Ichiro Yonenaga ◽  
Andrey Nikolaev ◽  
Yuriy Melnik ◽  
Vladimir Dmitriev
Keyword(s):  
Single Crystal ◽  
Room Temperature ◽  
Applied Load ◽  
Elevated Temperatures ◽  
Mechanical Stability ◽  
Bulk Single Crystal ◽  
Indentation Method ◽  
Temperature Range ◽  
Average Hardness ◽  
High Mechanical Stability

AbstractThe hardness of single-crystal aluminum nitride (AlN) 0.5-mm-thick wafers was measured at elevated temperatures and compared with that of other semiconductors. A Vickers indentation method was used to determine the hardness under an applied load of 0.5 – 5 N in the temperature range 20 - 1400°C. The average hardness was measured as 17.7 GPa at room temperature, harder than GaN and InN. The fracture toughness is 0.5 MPa•m1/2. AlN exhibits the hardness higher than that of GaN in the entire temperature range investigated. Up to about 1100°C, AlN maintains its hardness and thus, a high mechanical stability for AlN at elevated temperatures is deduced.

Hardness of bulk single-crystal GaN and AlN

2002 ◽  
Vol 7 ◽  
Author(s):  
Ichiro Yonenaga
Keyword(s):  
Single Crystal ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Mechanical Stability ◽  
Indentation Hardness ◽  
Bulk Single Crystal ◽  
Vickers Indentation ◽  
Indentation Method ◽  
Nano Indentation ◽  
High Mechanical Stability

The hardness of single-crystal GaN and AlN of 0.5-mm-thickness was measured by the Vickers indentation method in the temperature range 20 - 1400°C. The hardness of GaN and AlN is 10.2 and 17.7 GPa, respectively, at room temperature. The nano-indentation hardness of single-crystal AlN was measured at room temperature as 18 GPa, harder than GaN and InN. Up to about 1100°C, GaN and AlN maintain its hardness similar to that of SiC and thus, a high mechanical stability for GaN and AlN at elevated temperatures is deduced. Yield strength of nitrides is discussed.

9 kV 4H-SiC IGBTs with 88 mΩ·cm2 of R diff, on

2007 ◽  
Vol 556-557 ◽  
pp. 771-774 ◽  
Author(s):  
Qing Chun Jon Zhang ◽  
Charlotte Jonas ◽  
Bradley Heath ◽  
Mrinal K. Das ◽  
Sei Hyung Ryu ◽  
...  
Keyword(s):  
High Temperature ◽  
Threshold Voltage ◽  
High Power ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Gate Bias ◽  
Channel Mobility ◽  
Fast Switching ◽  
Blocking Voltage ◽  
First Time

SiC IGBTs are suitable for high power, high temperature applications. For the first time, the design and fabrication of 9 kV planar p-IGBTs on 4H-SiC are reported in this paper. A differential on-resistance of ~ 88 m(cm2 at a gate bias of –20 V is achieved at 25°C, and decreases to ~24.8 m(cm2 at 200°C. The device exhibits a blocking voltage of 9 kV with a leakage current density of 0.1 mA/cm2. The hole channel mobility is 6.5 cm2/V-s at room temperature with a threshold voltage of –6.5 V resulting in enhanced conduction capability. Inductive switching tests have shown that IGBTs feature fast switching capability at both room and elevated temperatures.

scholarly journals Matrix design of a novel ductile cast iron modified by W and Al: A comparison between thermodynamic modeling and experimental data

10.30544/449 ◽  
2020 ◽  
Vol 26 (1) ◽  
pp. 15-29
Author(s):  
Gülşah Aktaş Çelik ◽  
Maria-Ioanna T. Tzini ◽  
Şeyda Polat ◽  
Şaban Hakan Atapek ◽  
Gregory N. Haidemenopoulos
Keyword(s):  
Cast Iron ◽  
High Temperature ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Mechanical Stability ◽  
Low Cost ◽  
Equilibrium Temperature ◽  
Ductile Cast Iron ◽  
Thermal Expansivity ◽  
Thermodynamic Calculations

In high-temperature applications of ferrous materials, as in the case of exhaust manifolds, high thermal and mechanical stability are required. Stainless steels and Ni-resist alloys having austenitic matrices are good candidates to meet these requirements at elevated temperatures; however, they are expensive materials and present difficulties in casting. Ferritic ductile cast irons, like the commercial SiMo alloy, are comparatively cheaper materials with better castability but they cannot be used above approximately 800 °C. Thus, to meet the requirements with low-cost materials having improved high-temperature properties, new alloys must be developed by ferrite forming elements having the potential to increase equilibrium temperature. In this study, initially, a novel ductile cast iron matrix was designed using 1 W and 0-4 Al wt.-% and their phases stable at room temperature, transformation temperatures, solidification sequences and thermal expansivity values were determined using thermodynamic calculations with Thermo-Calc software. Computational studies revealed that (i) designed alloy matrices had graphite and M6C type carbides embedded in a ferritic matrix at room temperature as expected, (ii) A1 temperature increased as aluminum content increased. The obtained values were all above that of commercial SiMo alloy, (iii) the detrimental effect of increased aluminum addition on graphite content, and thermal expansivity was observed. Secondly, microstructural and thermal characterizations of cast alloys were performed for validation – the obtained data were in good agreement with the thermodynamic calculations.

Mechanical Properties and Dislocation Structure of Single Crystal Cdte Deformed in Compression at 300°C

1976 ◽  
Vol 34 ◽  
pp. 592-593
Author(s):  
Ernest L. Hall ◽  
J. B. Vander Sande
Keyword(s):  
Mechanical Properties ◽  
Single Crystal ◽  
Dislocation Structure ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Strain Curve ◽  
Optical Devices ◽  
Semiconductor Compound ◽  
Wide Range ◽  
Sample Orientation

The present paper describes research on the mechanical properties and related dislocation structure of CdTe, a II-VI semiconductor compound with a wide range of uses in electrical and optical devices. At room temperature CdTe exhibits little plasticity and at the same time relatively low strength and hardness. The mechanical behavior of CdTe was examined at elevated temperatures with the goal of understanding plastic flow in this material and eventually improving the room temperature properties. Several samples of single crystal CdTe of identical size and crystallographic orientation were deformed in compression at 300°C to various levels of total strain. A resolved shear stress vs. compressive glide strain curve (Figure la) was derived from the results of the tests and the knowledge of the sample orientation.

FANSTEEL 85 METAL

Alloy Digest ◽  
1981 ◽  
Vol 30 (6) ◽  
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
Creep Strength ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Base Alloy ◽  
Heat Treating ◽  
Good Combination ◽  
Bend Strength ◽  
Temperature Performance

Abstract FANSTEEL 85 METAL is a columbium-base alloy characterized by good fabricability at room temperature, good weldability and a good combination of creep strength and oxidation resistance at elevated temperatures. Its applications include missile and rocket components and many other high-temperature parts. This datasheet provides information on composition, physical properties, microstructure, hardness, elasticity, tensile properties, and bend strength as well as creep. It also includes information on low and high temperature performance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Cb-7. Producer or source: Fansteel Metallurgical Corporation. Originally published December 1963, revised June 1981.

scholarly journals Bi-Functional Composting the Sulfonic Acid Based Proton Exchange Membrane for High Temperature Fuel Cell Application

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1000
Author(s):  
Guoxiao Xu ◽  
Juan Zou ◽  
Zhu Guo ◽  
Jing Li ◽  
Liying Ma ◽  
...  
Keyword(s):  
High Temperature ◽  
Fuel Cell ◽  
Composite Membrane ◽  
Sulfonic Acid ◽  
Elevated Temperatures ◽  
Mechanical Stability ◽  
Strong Dependence ◽  
Proton Exchange ◽  
Nafion Membrane ◽  
Silica Nanofiber

Although sulfonic acid (SA)-based proton-exchange membranes (PEMs) dominate fuel cell applications at low temperature, while sulfonation on polymers would strongly decay the mechanical stability limit the applicable at elevated temperatures due to the strong dependence of proton conduction of SA on water. For the purpose of bifunctionally improving mechanical property and high-temperature performance, Nafion membrane, which is a commercial SA-based PEM, is composited with fabricated silica nanofibers with a three-dimensional network structure via electrospinning by considering the excellent water retention capacity of silica. The proton conductivity of the silica nanofiber–Nafion composite membrane at 110 °C is therefore almost doubled compared with that of a pristine Nafion membrane, while the mechanical stability of the composite Nafion membrane is enhanced by 44%. As a result, the fuel cell performance of the silica nanofiber-Nafion composite membrane measured at high temperature and low humidity is improved by 38%.

Martensite decomposition during post-heat treatments and the aging response of near-α Ti–6Al–2Sn–4Zr–2Mo (Ti-6242) titanium alloy processed by selective laser melting (SLM)

2021 ◽  
pp. 2050018
Author(s):  
Haiyang Fan ◽  
Yahui Liu ◽  
Shoufeng Yang
Keyword(s):  
Titanium Alloy ◽  
High Temperature ◽  
Titanium Alloys ◽  
Selective Laser Melting ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Aging Treatment ◽  
Water Quenching ◽  
Laser Melting ◽  
Aging Response

Ti–6Al–2Sn–4Zr–2Mo (Ti-6242), a near-[Formula: see text] titanium alloy explicitly designed for high-temperature applications, consists of a martensitic structure after selective laser melting (SLM). However, martensite is thermally unstable and thus adverse to the long-term service at high temperatures. Hence, understanding martensite decomposition is a high priority for seeking post-heat treatment for SLMed Ti-6242. Besides, compared to the room-temperature titanium alloys like Ti–6Al–4V, aging treatment is indispensable to high-temperature near-[Formula: see text] titanium alloys so that their microstructures and mechanical properties are pre-stabilized before working at elevated temperatures. Therefore, the aging response of the material is another concern of this study. To elaborate the two concerns, SLMed Ti-6242 was first isothermally annealed at 650[Formula: see text]C and then water-quenched to room temperature, followed by standard aging at 595[Formula: see text]C. The microstructure analysis revealed a temperature-dependent martensite decomposition, which proceeded sluggishly at [Formula: see text]C despite a long duration but rapidly transformed into lamellar [Formula: see text] above the martensite transition zone (770[Formula: see text]C). As heating to [Formula: see text]C), it produced a coarse microstructure containing new martensites formed in water quenching. The subsequent mechanical testing indicated that SLM-built Ti-6242 is excellent in terms of both room- and high-temperature tensile properties, with around 1400 MPa (UTS)[Formula: see text]5% elongation and 1150 MPa (UTS)[Formula: see text]10% elongation, respectively. However, the combination of water quenching and aging embrittled the as-built material severely.

scholarly journals Comparison of Mechanical and Microstructural Properties of as-Cast Al-Cu-Mg-Ag Alloys: Room Temperature vs. High Temperature

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1330
Author(s):  
Muhammad Farzik Ijaz ◽  
Mahmoud S. Soliman ◽  
Ahmed S. Alasmari ◽  
Adel T. Abbas ◽  
Faraz Hussain Hashmi
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Mechanical Testing ◽  
Tensile Testing ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Microstructural Properties ◽  
Testing Environments ◽  
Mechanical And Microstructural Properties ◽  
Mg Content

Unfolding the structure–property linkages between the mechanical performance and microstructural characteristics could be an attractive pathway to develop new single- and polycrystalline Al-based alloys to achieve ambitious high strength and fuel economy goals. A lot of polycrystalline as-cast Al-Cu-Mg-Ag alloy systems fabricated by conventional casting techniques have been reported to date. However, no one has reported a comparison of mechanical and microstructural properties that simultaneously incorporates the effects of both alloy chemistry and mechanical testing environments for the as-cast Al-Cu-Mg-Ag alloy systems. This preliminary prospective paper presents the examined experimental results of two alloys (denoted Alloy 1 and Alloy 2), with constant Cu content of ~3 wt.%, Cu/Mg ratios of 12.60 and 6.30, and a constant Ag of 0.65 wt.%, and correlates the synergistic comparison of mechanical properties at room and elevated temperatures. According to experimental results, the effect of the precipitation state and the mechanical properties showed strong dependence on the composition and testing environments for peak-aged, heat-treated specimens. In the room-temperature mechanical testing scenario, the higher Cu/Mg ratio alloy with Mg content of 0.23 wt.% (Alloy 1) possessed higher ultimate tensile strength when compared to the low Cu/Mg ratio with Mg content of 0.47 wt.% (Alloy 2). From phase constitution analysis, it is inferred that the increase in strength for Alloy 1 under room-temperature tensile testing is mainly ascribable to the small grain size and fine and uniform distribution of θ precipitates, which provided a barrier to slip by deaccelerating the dislocation movement in the room-temperature environment. Meanwhile, Alloy 2 showed significantly less degradation of mechanical strength under high-temperature tensile testing. Indeed, in most cases, low Cu/Mg ratios had a strong influence on the copious precipitation of thermally stable omega phase, which is known to be a major strengthening phase at elevated temperatures in the Al-Cu-Mg-Ag alloying system. Consequently, it is rationally suggested that in the high-temperature testing scenario, the improvement in mechanical and/or thermal stability in the case of the Alloy 2 specimen was mainly due to its compositional design.

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