Structure of quenched Zr-Pd alloys and the formation of the ω phase in zirconium alloys

Abstract

Methods of X-ray diffraction, optical metallography, transmission electron microscopy, and measurements of hardness and microhardness have been used to study the structure of quenched alloys of the zirconium-palladium system with a palladium concentration from 1 to 10 at %. It has been established that at the palladium content below 4 at % in the process of quenching in these alloys a eutectoid decomposition occurs and a two-phase structure is formed, which consists of laths of the α phase and particles of an intermetallic compound Zr2Pd arranged predominantly at the boundaries of laths of the α phase. In the alloys with a palladium content from 5 to 8 at %, there is formed a metastable ω phase. In the alloys with a palladium concentration of 9 and 10 at %, a metastable β phase is revealed. A method of determining the concentration of the alloying component in the ω phase is proposed. It is shown that in the quenched state this concentration is less than the content of the alloying component in the alloy. The behavior of the concentration boundary corresponding to the formation of the ω phase in binary zirconium alloys has been determined depending on the type of the alloying metal.