Vertical section phase diagrams of La-Fe-B ternary system
(1. Guangxi Key Laboratory of Information Materials, School of Materials Science and Engineering, Guilin University of Electronic Technology, Guilin 541004, China;
2. School of Physical Science and Technology, Guangxi University, Nanning 530004, China;
3. Guangxi Key Laboratory of Processing for Non-ferrous Metals and Featured Materials, Nanning 530004, China)
2. School of Physical Science and Technology, Guangxi University, Nanning 530004, China;
3. Guangxi Key Laboratory of Processing for Non-ferrous Metals and Featured Materials, Nanning 530004, China)
Abstract: The vertical sections of the La-Fe-B system were investigated using electron probe microanalysis and differential thermal analysis. Based on the microstructures and phase compositions of the as-cast and equilibrium alloys, together with their heat flow-temperature curves, phase diagrams for three vertical sections were drawn: LaxFe82By (x+y=18), LaxFe70By (x+y=30) and LaxFe53By (x+y=47), where x and y represent mass fraction of La and B, respectively, % . Additionally, according to the phase diagrams, the compound La2Fe14B was identified as a stable phase at high temperatures. It was found to be stable between 926.2 and 792.6 °C; at low temperatures, however, it decomposed into α-La, α-Fe and LaFe4B4, according to the reaction La2Fe14B→α-Fe+α-La+LaFe4B4.
Key words: solidification characteristics; vertical section phase diagram; equilibrium alloy; high temperature stable compound