A Study of Creep in Polysilicon MEMS Devices

2005 ◽  
Vol 127 (1) ◽  
pp. 90-96 ◽  
Author(s):  
K. Tuck ◽  
A. Jungen ◽  
A. Geisberger ◽  
M. Ellis ◽  
G. Skidmore
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
High Temperature ◽  
Creep Rate ◽  
Region Of Interest ◽  
Material Behavior ◽  
Mems Devices ◽  
Test Device ◽  
Micro Scale ◽  
Moderate Stress

Plastic deformation of polysilicon at high temperatures under stress due to creep has been demonstrated at the micro scale. This type of material behavior is generally associated with mechanical failure, however it can also be used to permanently deform or position a device. In order for creep in polysilicon to be used for MEMS applications its mechanical properties must be investigated. In this work, an experimental micro test structure is developed and measurements of high temperature plastic deformation within polysilicon are conducted. Both increases in temperature and stress are shown to increase the creep rate within the studied beams in the region of interest of the test device. Immediate plastic deformation of polysilicon has been observed to start at approximately 63% of the absolute melting temperature under moderate stress.

Intermetallics of Aluminum

2019 ◽  
Author(s):  
Georg Frommeyer ◽  
Sven Knippscheer
Keyword(s):  
Crystal Structure ◽  
Mechanical Properties ◽  
Plastic Deformation ◽  
High Temperature ◽  
Physical Properties ◽  
Intermetallic Compounds ◽  
Oxidation Behavior ◽  
Physical And Mechanical Properties ◽  
Structural Materials

Aluminum-rich intermetallic compounds of the Al3X-type with transmission metals (X = Ti. Zr, Nb, V) of Groups IVb and Vb are of interest in the development of novel high-temperature and lightweight structural materials. This article describes the important physical and mechanical properties of trialuminides with DO22 structure and their L12 variations. Topical coverage includes: crystal structure and selected physical properties, plastic deformation, oxidation behavior, and applications.

Effect of hot forming on anisotropy of mechanical properties of high-temperature 901 alloy

2021 ◽  
pp. 459-463
Author(s):  
A.V. Pchel'nikov ◽  
V.A. Filyakova ◽  
A.A. Sidorov
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
High Temperature ◽  
Hot Forming ◽  
Test Results ◽  
Initial Blank ◽  
Anisotropy Of Mechanical Properties

The effect of the macrostructure drawing after forming of blank made of high-temperature 901 alloy on the anisotropy of mechanical properties is studied. The effect of drawing on anisotropy is considered taking into account the unevenness of plastic deformation during upsetting and taking into account the deformation accumulated during the forging of the rod for the initial blank. The results of upsetting simulation and the test results of the samples mechanical properties cut in different directions of the blank fiber are presented.

Analysis of the Fundamental Mechanisms and Efficiency of the Deformation Methods of Nanostructuring

2008 ◽  
Vol 584-586 ◽  
pp. 29-34 ◽  
Author(s):  
Radik R. Mulyukov ◽  
Ayrat A. Nazarov ◽  
Renat M. Imayev
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
High Pressure ◽  
High Temperature ◽  
Severe Plastic Deformation ◽  
Grain Refinement ◽  
Equal Channel Angular Pressing ◽  
Efficient Method ◽  
High Pressure Torsion ◽  
Angular Pressing

Deformation methods of nanostructuring (DMNs) of materials are proposed to classify into severe plastic deformation (SPD) and mild plastic deformation (MPD) methods according to fundamentally different low- and high-temperature grain refinement mechanisms they exploit. A general analysis of the fundamentals and nanostructuring efficiency of three most developed DMNs, high pressure torsion (HPT), equal-channel angular pressing (ECAP), and multiple isothermal forging (MIF) is done with a particular attention to ECAP and MIF. It is demonstrated that MIF is the most efficient method of DMNs allowing one to obtain the bulkiest nanostructured samples with enhanced mechanical properties.

Microstructure and Mechanical Properties of AZ81 Magnesium Alloy after Unequal Channel Angular Pressing

2013 ◽  
Vol 749 ◽  
pp. 343-348
Author(s):  
Xiao Ping Luo ◽  
Ming Gang Zhang ◽  
Jun Qi Zhou
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Plastic Deformation ◽  
Tensile Strength ◽  
High Temperature ◽  
Magnesium Alloy ◽  
Pressing Temperature ◽  
Angular Pressing ◽  
Microstructure And Mechanical Properties ◽  
Tensile Fractures

The microstructure and mechanical properties of AZ81magnesium alloys after unequal channel angular pressing (UCAP) was investigated using self-made 90° die under different temperature. The results showed that under the same pressing speed, there was a better grain refinement and mechanical property improvement with the decreasing of pressing temperature, however, the tiny cracks on the surface of the processed samples increased. When squeezed at 250 , the average grain was refined from the initial 150um to10um. The tensile strength was changed to 350Mpa, and the elongation was of 10. Tensile fractures presented the increment of dimples structure, which was the result of refined α-Mg matrix and intermetallic compound β-Mg17Al12 phase by severe shear and plastic deformation at high temperature press.

Effect of а Number of Transition Metals on the Cohesive Properties of Cr-Ni-Base Alloys

2016 ◽  
Vol 879 ◽  
pp. 1998-2002 ◽  
Author(s):  
V.N. Butrim ◽  
V.I. Razumovskiy ◽  
A.G. Beresnev ◽  
A.S. Trushnikova ◽  
I.M. Razumovskii
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
High Temperature ◽  
Ab Initio Calculations ◽  
Base Alloy ◽  
Two Phase ◽  
Alloying Additions ◽  
High Temperature Mechanical Properties ◽  
Cohesive Properties ◽  
Theoretical Predictions

We used the results of ab initio calculations to improve the high temperature mechanical properties of a Cr-Ni-base alloy (Cr-33Ni-2W-0,3Ti-0,3V, wt.%) (alloy I) with two-phase α - γ microstructure. It was established that γ – phase in Cr-Ni-base alloy (I) plays a key role in the processes of plastic deformation. By analogy with Ni-base superalloys the bulk and grain boundaries cohesion in γ – phase of the Cr-Ni-base alloy (I) were strengthened by adding a package of the “low alloying” elements (Zr, Hf, Nb, Ta) (alloy II) chosen in accordance with our theoretical predictions. We further investigated an influence of a sum (Ta, Nb, Hf, Zr) like the low alloying additions on the mechanical properties of Cr-Ni-base alloy (I). The results of mechanical testing revealed a significant strengthening of the alloy (II) in comparison with (I) at the temperature 1080 oC in accordance with our predictions. We also investigated the microstructure’s peculiarities of the alloys (I) and (II).

Mechanical properties of near alpha titanium alloys for high-temperature applications - a review

2020 ◽  
Vol 92 (4) ◽  
pp. 521-540 ◽  
Author(s):  
Vitus Mwinteribo Tabie ◽  
Chong Li ◽  
Wang Saifu ◽  
Jianwei Li ◽  
Xiaojing Xu
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
High Temperature ◽  
Titanium Alloys ◽  
Content Type ◽  
The Past ◽  
Ti Alloys ◽  
Multiaxial Compression ◽  
Aero Engines ◽  
Temperature Applications

Purpose This paper aims to present a broad review of near-a titanium alloys for high-temperature applications. Design/methodology/approach Following a brief introduction of titanium (Ti) alloys, this paper considers the near-α group of Ti alloys, which are the most popular high-temperature Ti alloys developed for a high-temperature application, particularly in compressor disc and blades in aero-engines. The paper is relied on literature within the past decade to discuss phase stability and microstructural effect of alloying elements, plastic deformation and reinforcements used in the development of these alloys. Findings The near-a Ti alloys show high potential for high-temperature applications, and many researchers have explored the incorporation of TiC, TiB SiC, Y2O3, La2O3 and Al2O3 reinforcements for improved mechanical properties. Rolling, extrusion, forging and some severe plastic deformation (SPD) techniques, as well as heat treatment methods, have also been explored extensively. There is, however, a paucity of information on SiC, Y2O3 and carbon nanotube reinforcements and their combinations for improved mechanical properties. Information on some SPD techniques such as cyclic extrusion compression, multiaxial compression/forging and repeated corrugation and straightening for this class of alloys is also limited. Originality/value This paper provides a topical, technical insight into developments in near-a Ti alloys using literature from within the past decade. It also outlines the future developments of this class of Ti alloys.

Mechanical Properties of Bulk Glassy Metal after Deformation under High Temperature Conditions

2007 ◽  
Vol 340-341 ◽  
pp. 113-118
Author(s):  
Takamasa Yoshikawa ◽  
Masataka Tokuda ◽  
Tadashi Inaba
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
High Temperature ◽  
Room Temperature ◽  
Tensile Load ◽  
Experimental Result ◽  
Uniaxial Tensile ◽  
Heating Process ◽  
Plastic Behavior ◽  
Temperature Conditions

Bulk glassy metal is an alloy with the vitreous amorphous structure. Because of various excellent properties, this material is expected to use as an alternative structural material for several engineering applications very well. Although bulk glassy metal is very little deformed plastically in the room temperature, it shows the huge super-plastic behavior over the high temperature. However, there is not many reports mentioned about the mechanical properties of bulk glassy metal after plastic deformation under high temperature condition. From the above point of view, in this study, we have investigated the lower bound of temperature at which Zr55Cu30Al10Ni5 bulk glassy metal can be plastically deformed in uniaxial tensile load. Furthermore, it is focused on the strength property of bulk glassy metal in the room temperature after deformed under various high-temperature conditions. In the experimental result, when this material was heated at temperature of 685[K] or higher, this material crystallized and the mechanical strength in room temperature drastically decreased to 200[MPa], although this material as cast had the strength over 1500[MPa]. However, this material showed sufficiently the plastic deformation at temperatures of 643[K] and the strength in room temperature after cooling was equal to as cast. It is supposed that the strength depend on its atomic structure, i.e., amorphous or crystalline, and the change of its structure is affected strongly by heating process.

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