In situ diffraction experiments in two-phase magnesium alloys

Orateur : Elvira ONORBE ESPARRAGUERA (National Center for Metallurgical Research CENIM-CSIC and Research Center for Energy, Environment and Technology CIEMAT, MADRID)

Magnesium alloys present great potential as structural materials in the aerospace and automobile industries, mainly because of their low density and high specific strength. However, due to their rapid loss of strength at temperatures above room temperature and their poor creep resistance at high temperatures, magnesium alloys are rarely used above 200 °C. There is a great interest in developing new magnesium alloys with superior creep resistance at intermediate temperatures. On one hand the addition of stiffer phases such as ceramic or metallic particles, ceramic or carbon fibres to magnesium alloys improves their high temperature creep resistance and leads to an increase in their tensile strength, Young´s modulus, hardness (particularly at room temperature) and wear resistance. On the other hand the addition of yttrium and/or rare earths elements favours the formation of intermetallic phases which are stable up to high temperature. Due to the strong influence of the crystallographic texture in the plastic deformation of the magnesium alloys and magnesium matrix composite, it is difficult to evaluate the role of the load transfer mechanism in the strength of the two phase magnesium alloys. The aim of this work is to measure the internal strains using Synchrotron Radiation Diffraction during in-situ tensile and compressive tests in two kind of two-phase magnesium alloys : - AZ31 alloy reinforced with SiC particles or whiskers. - New Mg-Y-Zn alloys containing Long Period Stacking Ordered structures (LPSO) phases.

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