Constitution of ZrCo–ZrIr alloys

Semenova, O.; Kudryavtsev, Y. V.; Petyukh, V. М.; Samelyuk, A. V.

doi:10.1007/s11106-011-9288-y

Cited by 2 publications

(1 citation statement)

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“…Using resistometric data for the ZrCo-ZrIr alloys with 1-10 Co (Figs. 4 and 5), we determined the alloy composition at which the high-temperature phase was stable at room temperature: 35 at.% Ir [14]. The stabilization effect of cobalt is much weaker in the ZrCo-ZrNi alloys formed by components that have metallochemical characteristics close to those of ZrCo-ZrIr: the B2 phase was observed at 14-20 at.% Ni [15].…”

Section: Resultsmentioning

confidence: 99%

Shape memory effect in ZrIr and Zr-Ir-Co alloys

Kudryavtsev

Semenova

2011

Powder Metall Met Ceram

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The paper examines the capability of ZrIr alloys, which undergo martensitic transformation at temperatures higher than 700°C, to develop thermomechanical properties accompanying the transformation. The ZrIr sample is found to recover its shape, after being deformed, during heating at a rate of 100°C/sec to temperatures higher than the martensitic transformation temperature. The Zr-Ir-Co ternary alloy shows the same property when heated at a rate of about 1-2 °C/sec. The temperature dependence of resistivity of these alloys is considered.Shape memory alloys are metal compounds that exhibit special mechanical properties associated with martensitic transformation (MT) driven, particularly, by temperature. These properties owe to the capability of such alloys to recover their shape during heating after preliminary deformation. For TiNi alloys, the most well-known shape memory compounds, this capability can be substantial, reaching 8-10% and promoting their wide application. A significant restriction in the use of these alloys is a low upper temperature limit of transformation (∼100°C), which contradicts the requirements on materials for high-temperature applications, for example, aerospace engineering Doping of TiNi with metals such as Pt, Pd, and Hf [1-3] is one of the ways to produce alloys that exhibit special thermomechanical properties at temperatures close to 500°C. Another way is to use alloys based on equiatomic compounds formed by transition metals of groups IV and V and platinum group metals, which are characterized by higher temperatures of phase transformations responsible for the shape memory effect (SME). These compounds are similar in that they, like TiNi, have a high-temperature modification with a B2-type crystal structure transforming into a low-temperature orthorhombic or monoclinic modification with decreasing temperature. It was reported previously [4-8] that transformation in some of these compounds, for example ZrRh, TiRh, NbRu, and TaRu, is accompanied, like in TiNi, by shape recovery after deformation.There is information on the phase equilibria and attempts to evaluate the thermoelastic properties of ZrIr alloys [4,9,10].The x-ray diffraction pattern of the equiatomic Zr-Ir alloy at room temperature was identified in [11] to belong to an individual phase with its own type of crystal structure, the same as ZrRh. The structural identity of the high-temperature ZrRh and ZrIr phases (cubic, CsCl type, ZrIr lattice parameter a = 0.3318 nm at 1050°C) and of the low-temperature phases was ascertained in [4,12]. The structure of the ZrIr phase at room temperature is defined as monoclinic of B19′type (like in TiNi) with lattice parameters a = 0.333 nm, b = 0.438 nm, and c = 0.535 nm,

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Section: Resultsmentioning

confidence: 99%