Morrison, Keith R. M.S.M.S.E., Purdue University, August 2014. Nickel Aluminum Shape Memory Alloys via Molecular Dynamics. Major Professor: Alejandro Strachan. Shape memory materials are an important class of active materials with a wide range of applications in the aerospace, biomedical, and automobile industries. These materials exhibit the two unique properties of shape memory and superelast...

In order to gain a better understanding of the formation of plessite in iron meteorites, various electron optical techniques were employed to study the range of plessite structures observed in the Carlton fine octahedrite. Compositional and structural studies of twins in clear taenite and the cloudy zone were made. Transmission electron microscopy studies of martensitic and duplex a + y plessit...

The damping characteristics of Ti50Ni50-xCux (x = 0~30 at.%) shape memory alloys (SMAs) at a low frequency have been studied using a dynamic mechanical analyzer. The magnitude of the tan δ value and the values of the storage modulus (E₀) softening/hardening and the strain variation exhibited in B2↔B19 transformation are all higher than those in B2↔B19' transformation. The larger E₀ softening/ha...

The microstructure and properties of a 5 wt.% Cr cold work tool steel were studied after austenitisation at 1020°C, 1050°C or 1075°C followed by single, double and triple tempering treatments at 525°C. The microstructures were investigated with scanning electron microscopy and X-ray diffraction and phase transformations were studied by dilatometry. Furthermore, hardness and Charpy un-notched an...

Cryogenic treatment (CT) is the supplementary process to conventional heat treatment process in steels, by deep–freezing materials at cryogenic temperatures to enhance the mechanical and physical properties of materials being treated. Cryogenic treatment (CT) of materials has shown significant improvement in their properties .Various advantages like increase in hardness, increase in wear resist...

Abstract The work presents results on the effect of prior martensite formation bainite transformation kinetics in a 3% medium-Mn multiphase steel. material was subjected to two isothermal holding temperatures: 400 °C (without martensite) and 350 (with martensite). According obtained dilatometric results, leads acceleration kinetics. starts finishes much faster, when present before holding. micr...

There are precise observations which indicate the reluctance of excess carbon within bainite or martensite to partition into adjacent austenite in spite of prolonged heat treatment at temperatures where carbon is mobile. To explain this, we report the first calculations of the solubility of carbon in tetragonal ferrite that is in equilibrium with austenite. It is found that the solubility is dr...

austenite is a semi-stable phase in most stainless steels that deforms to martensite under md30 and forms martensitetype ά and ε due to the deformation in the steels. since the distribution of strain induced martensite plays animportant role in achieving desired properties, the main objective of the present work is to model martensitedistribution of ά during cold rolling using finite element me...

In this study the α′′ stress-induced martensitic transformation and damping behaviour of the superelastic β-Ti–25Ta–25Nb alloy are investigated by tensile tests at room temperature and by dynamic mechanical analysis (DMA) in tensile mode for different applied stresses. Tensile tests show a fully non-linear elastic domain and, consequently, a specific method is proposed to determine the elastic ...

The quantitative characterization of the microstructure evolution in high-Mn steel during deformation is of great importance to understanding its strain-hardening behavior. In the current study, in situ high-energy synchrotron X-ray diffraction was employed to characterize the microstructure evolution in a Fe-17Mn-1.5Al-0.3C steel during a tensile test. The microstructure at different engineeri...