Deformation Twinning Avalanche Behavior and Macroscopic Yield Stress in Polycrystalline Pure Ti

The aim of present study is to investigate the relationship between deformation twinning avalanche behavior and macroscopic yield stress arising in polycrystalline pure Ti under mechanical loading. First, a commercial polycrystalline pure Ti palate is prepared, and the two types of micropillar specimens are fabricated from the plate. One is single crystal and bicrystal micropillar specimens which size is several micro meter, fabricated by Focus Ion Beam (FIB) technique. The other is polycrystalline micropillar specimens which size is from several dozen to several hundred micro meter, fabricated by in-house processing machine. Second, compression tests are performed by in-house micro compression test machines for the micropillar specimens. At the same time, acoustic emission (AE) monitoring is conducted to measure deformation twinning initiation. The relationship between deformation twinning avalanche behavior and macroscopic yield stress arising in polycrystalline pure Ti is discussed from the present experimental results.