Engineering Applications and Devices: Session 3
Program Organizers: Alan Pelton, G.RAU Inc.
Thursday 9:00 AM
July 13, 2017
Room: Gold Coast
Location: Hyatt Regency Chicago
Session Chair: Huilong Hou, University of Maryland, College Park
SMA Microactuators for In situ TEM Strain Analysis: Christoph Chluba1; Ulrich Schürmann1; Niklas Wolff1; Rodrigo Lima de Miranda2; Daria Smazna1; Rainer Adelung1; Lorenz Kienle1; Eckhard Quandt1; 1University of Kiel; 2Acquandas GmbH
In situ straining TEM analysis is a useful tool in materials science to investigate deformation mechanisms and stress induced transformations on the atomistic scale. Here we present a simple method for in situ straining experiments by using micro SMA actuators implemented in a TEM grid fabricated by thin film technology and sputter deposition of NiTi-based alloy compositions. Actuation during the experiment is performed by a slight temperature change (~40 K) of the grid which is either conducted by using a conventional heating holder or by local resistive heating. Depending on the microactuator design displacements of several 100 µm with forces up to 0.5 N can be achieved. Moreover a linear actuation movement with temperature change is observed which facilitates the strain control. To demonstrate the capability of this new concept first in situ straining TEM experiments for different materials like e.g. ZnO are presented.
Role of Precipitates on the Formation of Recovery Stresses in FeMnSi based Shape Memory Alloys for Pre-stressing Applications: Ariyan Arabi-Hashemi1; Christian Leinenbach1; 1Empa - Swiss Federal Laboratories for Materials Science and Technology
In the recent years, FeMnSi based shape memory alloys (SMA) have attracted significant interest due to their potential for engineering applications such as seismic damping or element reinforcing. The present contribution investigates the role of precipitates, here exemplarily VC, on the recovery stress formation in restrained samples of the Fe–17Mn–5Si–10Cr–4Ni–1(V,C) (ma.-%) SMA. We show that the recoverable strain and the recovery stress are affected in different ways by the precipitate size and that the latter one has to be chosen carefully in order to optimize the recovery stress. By tuning the shape memory effect and matrix strength through changing the precipitate size in different heat treatments we achieved a recovery stress of more than 550 MPa using a comparably low heating temperature of 160°C which allows using the alloy for pre-stressing elements in concrete structures.
Features Cavitation Resistance of Multifunctional Coatings from Materials with a Shape Memory Effect: Dmitriy Dmitrenko1; Blednova Zhesfina1; Balaev Etibar1; 1Kuban state technological University
It is established on the basis of the analysis of structural components of criterion of cavitation resistance of multifunctional coatings from materials with a shape memory effect (SME) that the major factors influencing the cavitation resistant coatings are: tendency to straining hardening, reversible deformation, the adhesion strength, microhardness, uniformity of structure and roughness’s of a surface. Weights coefficients for assessment of influence of each of the specified components are defined. The mechanism of enhancing of cavitation resistance of coatings from materials with SME based on structural and phase transformations in the coating material, subject to local cavitation effects. Tests on cavitation resistance of multilayer coatings of materials with SME performed according to standard methods of analysis of structural-phase state and functional-mechanical properties that they are allowed to recommend as a cavitation-resistant. Architecture layered surface composition is proposed, which provides increase of durability of products in the conditions of cavitation-abrasive environment.
10:00 AM Break