MSE Seminar: Xinpeng Du, The rebuilt of elastic constants from polycrystalline samples by measuring velocities of surface acoustic waves induced by ultrafast laser

Abstract

Elastic constants are extremely important property to understand mechanical behavior of materials and are also very fundamental and indispensable inputs for physics-based models. Many experimental methods are put forward to measure elastic constants of materials but most of them are on single crystal samples directly, which brings strict requirements on sample size, sample geometry, sample homogeneity and multiple sample orientations in preparations. As a result, experimental values of elastic constants of about 99% solid solutions and compounds (roughly 160,000 kinds) are unavailable, which reveals tremendous limitations of traditional experimental methods. In order to make a breakthrough, we developed an innovative experimental method in rebuilding the elastic constants of a material from its polycrystalline sample by detecting surface acoustic waves induced by ultrafast laser on its surface. This method not only frees us from growing single crystals but also guarantees higher spatial resolution in tests, which makes it applicable in obtaining microstructure or composition dependent elastic constants properties through local measurements. In the end, accurate and repeatable benchmark work are provided to verify this method and several applications are proposed to prove its advantages.

Bio

Xinpeng Du got his Bachelor’s degree from Zhejiang University in 2011 majoring in optical engineering. He began his PhD study at OSU in the same year and has worked with professor Ji-Cheng Zhao at MSE since then. Xinpeng’s field is to develop an innovative method in locally measuring elastic constants with high spatial resolution. He works on both simulation and experiments. So far he has completed a benchmark work on several metals of cubic crystal class. He has also extended the application to get the elastic constants as a function of composition by doing experiments on diffusion couples and also has succeeded in obtaining elastic constants from powder samples experimentally. Right now, he is working on measuring elastic constants of intermetallic compound of low-symmetry crystals.