Understanding the Strengthening Effect of β1 Precipitates in Mg-Nd Using In Situ Synchrotron X-ray Diffraction
In situ synchrotron x-ray diffraction was carried out at beamline BL14B1 of Shanghai Synchrotron Radiation Facility (SSRF) to study the tensile deformation of an extruded Mg-2.2 wt.%Nd alloy before and after aging. The aged specimen that contained β1 (Mg3Nd) precipitates showed higher strength than the nonaged specimen, while the strain to failure of the two specimens was almost equal. Analysis of the lattice strain evolution in the aged specimen revealed a modest load-transfer effect from Mg to β1 after 2% strain. Peak width analysis indicated that a high level of microstrain developed in β1 immediately after material yielding. Ex situ transmission electron microscopy (TEM) showed strong interaction between basal dislocations and β1 precipitates. Based on these results, it is proposed that the extra strength in the aged specimen is caused by β1 impeding dislocation movement and eventually being sheared by dislocations.
This work is financially supported by the National Key Research and Development Program of China (No. 2016YFB0701203) and the National Natural Science Foundation of China (Nos. 51631006 and 51671127). L.W. is also sponsored by Shanghai Pujiang Program (No. 16PJ1404600). The authors thank beamline BL14B1 (Shanghai Synchrotron Radiation Facility) for providing beam time and help during experiments.
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