Phase Equilibria in the Ti–Ti5Si3–Dy5Si3–Dy Region of the Ti–Dy–Si System

    

I. M. Frantsevich Institute for Problems of Materials Science of the NAS of Ukraine, Omeliana Pritsaka str.,3, Kyiv, 03142, Ukraine
Powder Metallurgy - Kiev: Frantsevich Institute for Problems of Materials Science NASU, 2015, #07/08
http://www.materials.kiev.ua/article/1975

Abstract

Differential thermal analysis, X-ray diffraction, and metallography are employed to examine the phase equilibria in the Ti–Ti–Ti5Si3–Dy5Si3–Dy region of the Ti–Dy–Si system. Isothermal sections at 1100 and 900 °C, vertical sections at 5Si, 65Ti, and 65Dy isopleths, and a reaction scheme are constructed. The ternary compound TiDySi (τ) exists at experimental temperatures and has no appreciable homogeneity range. The isothermal sections at 1100 and 900 °C are similar and characterized by five three-phase regions (β + (α-Dy) + τ, β+ (Ti3Si) + τ, (Ti3Si) + τ + (Ti5Si3), (α-Dy) + τ + (Dy5Si3) and (Ti5Si3) + τ + (Dy5Si3)) and respective two-phase fields. Three invariant four-phase equilibria are found in solid state: β + (Ti5Si3) ⇄ (Ti3Si) + τ (U3), β + τ + (Ti3Si) ⇄ α (P2), and β + τ + (α-Dy) ⇄ α (P3) at ~1150, 900, and 885 °C, respectively. There is also a three-phase equilibrium, β + τα, at 845 °C (р4). The phase equilibria are summarized in the reaction scheme.


CRYSTALLIZATION SCHEME, ISOTHERMAL SECTIONS, LIQUIDUS SURFACE, MELTING DIAGRAM, SOLIDUS SURFACE, STATE DIAGRAM, VERTICAL SECTION