Effect of cyclic annealing heat treatment on tungsten particles and matrix interface in heavy tungsten alloy

مهندسی متالورژی و مواد

Article 1, Volume 35, Issue 4 - Serial Number 36, December 2024, Pages 1-18   

Document Type: Original Article

DOI: 10.22067/jmme.2024.88925.1151

Authors

Ali Harimi¹; gholamreza ebrahimi²; A Rezaie bazaz^{* 1}; Hasan Najafi¹; kazem Zuichi Turk²

¹Department of material science and engineering, Faculty of Engineering, Ferdowsi university of Mashhad, Mashhad, Iran.

²Department of material science and engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Iran.

Abstract

Heavy tungsten alloys are made by liquid phase sintering for application in protective weights, radiation shields, and anti-missiles. The change in each of the production parameters of these alloys affects the mechanical behavior of these alloys. The aim of this research is to assess the effect of annealing heat treatment cyclic on the bonding strength of tungsten particles with the matrix. Tungsten alloy with a chemical composition of 93.5W-5.4Ni-1.95Fe (in wt.%) is first compressed in a plastic mold (cold isostatic) following by liquid phase sintering at 1480 °C and two cycles of annealing heat treatment. In order to study the mechanical properties, tensile and hardness tests are used. Also, the microstructures and fracture surfaces (after tensile test) of the samples are examined using optical and scanning electron microscopes. The obtained results show that due to the thermal stresses during cooling and heating through the cyclic annealing heat treatment, the matrix phase is penetrated into the interface of tungsten particles which causes a decrease in the contiguity (from 0.44 to 0.31). Also, the cyclic annealing heat treatment reduces the impurities in the interface between tungsten particles and the matrix, resulting in an increase in strength (from 842 MPa to 960 MPa). Comparison of fracture surfaces of samples with annealing cyclic shows the change of brittle fracture mechanism to soft fracture. Keywords: Heavy tungsten alloys; Sintering; Heat treatment; Particles/matrix interface; Contiguity.

Keywords

Heavy tungsten alloys; particles/matrix interface; cyclic heat treatment; sintering; contiguity

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