Engineering Commons^™

Microstructural Analysis And High Temperature Creep Of Mo-9si-8b Alloys With Al And Ge Additions, Peter Kellner, Rainer Völkl, Uwe Glatzel

Beyond Nickel-Based Superalloys II

Refractory metals and their alloys show potential for high temperature applications, due to the increased melting point and creep resistance. Spark plasma sintering technology as well as argon arc melting is used to prepare quaternary and quinternary Mo-9Si-8B-xAl-yGe (x is 0 or 2; y is 0 or 2) samples. Compositions are stated in at.%. All the compositions consist of a Mo solid solution (α-Mo) and two intermetallic phases: Mo₃Si (A15) and Mo₅SiB₂ (T₂). On the one hand, no zirconium is added to the alloys to avoid evaporation of MoO₃ due to the …

Mo-9si-8b Alloys With Additons Of Zr – Microstructure And Creep Properties, Uwe Glatzel, Christian Hochmuth, Rainer Völkl

Beyond Nickel-Based Superalloys II

Three phase Mo-9Si-8B (at.%) alloys are a prominent example for a potential new high temperature structural material. Due to their high melting point and excellent creep resistance. In this study the effect of Zr addition (0…4 at.%) on the microstructure and creep properties of Mo-9Si-8B (at.%) alloys is investigated. Two powder metallurgical processes, hot isostatic pressing (HIP) and spark plasma sintering (SPS), are used to prepare specimens. The resulting microstructures are examined using SEM and TEM analysis. SPS alloys exhibit smaller grain sizes and fewer oxides compared to the HIP alloys, because of the oxygen availability during HIP. The more …

Microstructure And Creep Resistance Of Ti-Rich Mo + Mo5si3 + Mo5sib2 Alloys, Daniel Schliephake, Martin Heilmaier

Beyond Nickel-Based Superalloys II

New materials are necessary to increase efficiency of power generation and aircraft engines by higher combustion temperatures. Recently, it was found that alloying with high amounts of Ti replaces Mo₃Si by Mo₅Si₃ and stabilizes the phase field Mo + Mo₅Si₃ + Mo₅SiB₂, which could be beneficial for higher oxidation resistance, since Mo₅Si₃ is more oxidation resistant than Mo₃Si. Additional, Ti-rich Mo-Si-B alloys show an increased creep resistance compared to Ti-free Mo-Si-B alloys and a significant reduction in the alloy density. However, using the …

Microstructural Properties And Four-Point Bend Fatigue Behavior Of Ti-6.5al-2zr-1mo-1v Welded Joints By Electron Beam Welding, Peng Liu, Tongguang Zhai, Yuanbin Zhang

Chemical and Materials Engineering Faculty Publications

With the help of a four-point-bend of fatigue rig, high-cycle fatigue tests were carried out on an Ti–6.5Al–2Zr-1Mo-1V titanium alloy at room temperature, 20 Hz and R = 0.1 in ambient air. The test results indicated that the fatigue strength of base metal, 888 MPa, is about 120% of yield strength. The fatigue strength of joints is 814 MPa. It is about 110% of yield strength of base metal. When the loading stress is higher, the fatigue failure region is located in middle weld zone of weld face, which the cracks are propagated along coarse β phase’s grain boundary. When …

Microstructure And Rheology Of Carbon Nanotubes At Air-Water Interfaces, Charles D. Young

Honors Scholar Theses

This work characterizes the material properties of carbon nanotubes at air-water interfaces for potential use in creating stable emulsions. Properties such as length, aspect ratio, contact angle, microstructural ordering, surface pressure, compression and shear elastic moduli, stresses, surface viscosities and non-linearity are explored. Challenges such as deviation from a classical analysis of monolayers are encountered in the form of aggregation, mechanical contributions, and interface relaxation. These factors are taken into account to explain experimental measurements and trends. Ultimately, existing models for more homogeneous systems are resolved with observations to offer insight and areas of promise moving forward.

Coercivity Enhancement And Gamma Phase Avoidance Of Alnico Alloys, Li Zhang

Department of Engineering Mechanics: Dissertations, Theses, and Student Research

The promotion of social progress requires greater levels of energy efficiency, quality and productivity. However, these developments usually come at the cost of the environment. Green technologies such as electric vehicles, wind turbine and solar panels are ironically overshadowed by supply limitations and high prices of rare earth elements. Therefore, it is important to find alternative materials to replace those that contain critical elements. Alnico alloys show high magnetization, high Curie temperature (800°C) and good corrosion resistance, making it one of the best candidates to replace neodymium-based magnets used in electric vehicles.

In this thesis, methods controlling shape anisotropy and …

Field Tests Of Cement Fly-Ash Steel-Slag Pile Composite Foundation, Bing Zhang, Shuai Cui

Department of Civil, Environmental, and Geospatial Engineering Publications

Steel slag is one of the main waste materials in the steelmaking process. As a result, a tremendous amount of steel slag is produced and deposited into storing yards every year. Recycling of the abandoned steel slag is of great environmental and economic value. This study investigates the usage of steel-slag concrete with fly ash as a kind of composite foundation pile material, which can be applied to multi-pile composition foundations for ground improvement involving different pile types. The micromorphology of the concrete, which uses steel slag as aggregate, is analyzed using scanning electron microscopy (SEM). The bearing characteristics of …

Features Of Grain Growth And Grain Boundary Formation Under Microwave And Spark Plasma Sintering Conditions, Ostap Zgalat, Andrey Ragulya

Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium

The feedback properties of particulate nanomaterials versus their structure parameters (grain size, pore size), were found much more sensitive than that in conventional materials [1-3]. Among them field assisted sintering techniques including SPS and microwave sintering (MWS) were intensively developed [4-9]. The effect of inhibited grains growth for nanomaterials was established for Field Assisted Sintering Technology [4,5,8,9].

The FAST or Spark Plasma Sintering (SPS) is a rapid rate consolidation technology where effect of electromagnetic field enhanced by external pressure. The studies of FAST densification for nano-TiN shows the possibility to substantially inhibit the grain growth and fabricate materials with grains …

The Effects Of Thermal Procedure On Transformation Temperature, Crystal Structure And Microstructure Of Cu-Al-Co Shape Memory Alloy, Y. Aydoğdu, M. Kök, F. Dağdelen, A. Aydoğdu, Ali S. Turabi, Haluk E. Karaca

Mechanical Engineering Faculty Publications

The purpose of this study is to investigate the effects of different thermal procedures of the Cu-Al-Co shape memory alloy on its crystal structure, transformation temperature and microstructure. The alloys were subjected to a heat treatment and then cooling was applied at four different conditions. After the thermal process, XRD, DSC, optical microscopy and micro-hardness measurements were carried out. The experimental studies showed that crystal structure, microstructure and transformation temperature of Cu-Al-Co alloy were changed from the cooling conditions.

Effect Of Deformation On Microstructure And Mechanical Properties Of Dual Phase Steel Produced Via Strip Casting Simulation, Zhiping Xiong, Andrii Kostryzhev, Nicole Stanford, Elena V. Pereloma

Faculty of Engineering and Information Sciences - Papers: Part A

The strip casting is a recently appeared technology with a potential to significantly reduce energy consumption in steel production, compared to hot rolling and cold rolling. However, the quantitative dependences of the steel microstructure and mechanical properties on strip casting parameters are unknown and require investigation. In the present work we studied the effects of strain and interrupted cooling temperature on microstructure and mechanical properties in conventional dual phase steel (0.08C-0.81Si-1.47Mn-0.03Al wt%). The strip casting process was simulated using a Gleeble 3500 thermo-mechanical simulator. The steel microstructures were studied using optical, scanning and transmission electron microscopy. Mechanical properties were measured …

Microstructure And Micro-Texture Evolution During The Dynamic Recrystallisation Of A Ni-30fe-Nb-C Model Alloy, Parvez Mannan, Ahmed A. Saleh, Azdiar A. Gazder, Gilberto Casillas, Elena V. Pereloma

Faculty of Engineering and Information Sciences - Papers: Part A

The evolution of microstructure and micro-texture during discontinuous dynamic recrystallisation of an austenitic Ni-30Fe-Nb-C model alloy subjected to interrupted plane strain compression at strains (ε) of 0.23, 0.35, 0.68, 0.85 and 1.2 was investigated using electron backscattering diffraction and transmission electron microscopy. Throughout the strain range, the majority of dynamic recrystallisation events comprised nucleation in necklace-like arrangements located at and along grain boundaries via bulging. At ε ≥ 0.68, discrete nucleation events were also observed within grain interiors. Grain growth during dynamic recrystallisation is characteristic of strain induced boundary migration. The initial texture comprised Cube-RD ({013}〈100〉), Cube-ND ({001}〈310〉) and Cube …

The Heat Treatment Analysis Of E110 Case Hardening Steel, Majid Tolouei Rad, Eric Lichter

Research outputs 2014 to 2021

This paper investigates mechanical and microstructural behaviour of E110 case hardening steel when subjected to different heat treatment processes includingquenching, normalizing and tempering. After heat treatment samples were subjected to mechanical and metallographic analysisand the properties obtained from applying different processes were analysed. The heat treatment process had certain effects on the resultant properties andmicrostructures obtained for E110 steel which are described in details. Quenching produced a martensitic microstructure characterized by significant increase in material’s hardness and a significant decreased in its impact energy. Annealed specimens produced a coarse pearlitic microstructure with minimal variation in hardness and impact energy. For …

Influence Of Nb On The Β → Α″ Martensitic Phase Transformation And Properties Of The Newly Designed Ti-Fe-Nb Alloys, Shima Ehtemam-Haghighi, Yujing Liu, Guanghui Cao, Lai-Chang Zhang

Research outputs 2014 to 2021

A series of Ti-7Fe-xNb (x = 0, 1, 4, 6, 9, 11 wt.%) alloys was designed and cast to investigate the β → α″ martensitic phase transformation, β phase stability, the resulting microstructure and mechanical properties. Phase analysis revealed that only Ti-7Fe-11Nb alloy shows a single body-centred cubic β phase microstructure while the others are comprised of β and orthorhombic α″ phases. Moreover, Nb addition up to 11 wt.% enhances the stability and volume fraction of β phase in the microstructure, hence reducing the propensity of the alloy system to form α″ phase during quenching. Compressive yield strength and hardness …

Processing Of Al-12si-Tnm Composites By Selective Laser Melting And Evaluation Of Compressive And Wear Properties, Konda Prashanth, Sergio Scudino, Anil Chaubey, Lukas Löber, Pei Wang, Hooyar Attar, Frank Schimansky, Florian Pyczak, Jürgen Eckert

Research outputs 2014 to 2021

Al-12Si (80 vol%)-Ti52.4Al42.2Nb4.4Mo0.9B0.06 (at.%) (TNM) composites were successfully produced by the selective laser melting (SLM). Detailed structural and microstructural analysis shows the formation of the Al6MoTi intermetallic phase due to the reaction of the TNM reinforcement with the Al-12Si matrix during SLM. Compression tests reveal that the composites exhibit significantly improved properties (∼140 and ∼160 MPa higher yield and ultimate compressive strengths, respectively) compared with the Al-12Si matrix. However, the samples break at ∼6% total strain under compression, thus showing a reduced plasticity of the composites. Sliding wear tests were carried out for both the Al-12Si matrix and the Al-12Si-TNM …

Microstructure And Mechanical Properties Of Strip Cast Trip Steel Subjected To Thermo-Mechanical Simulation, Zhiping Xiong, Andrii Kostryzhev, Liang Chen, Elena V. Pereloma

Faculty of Engineering and Information Sciences - Papers: Part A

Instead of hot rolling and cold rolling followed by annealing, strip casting is a more economic and environmentally friendly way to produce transformation-induced plasticity (TRIP) steels. According to industrial practice of strip casting, rapid cooling in this work was achieved using a dip tester, and a Gleeble 3500 thermo-mechanical simulator was used to carry out the processing route. A typical microstructure of TRIP steels, which included ~0.55 fraction of polygonal ferrite with bainite, retained austenite and martensite, was obtained. The effects of deformation (0.41 reduction) above non-recrystallisation temperature, isothermal bainite transformation temperature and the size of second phase region on …