Volume 39, Issue 3 (Journal of Advanced Materials-Fall 2020)
2020, 39(3): 1-18 |
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Borouni A, Kermanpur A. Evaluating the Effect of Ta/W Ratio on Microstructure and Stress Rupture Properties of Ni-Based Single Crystal Superalloy PWA1483. Journal of Advanced Materials in Engineering (Esteghlal) 2020; 39 (3) :1-18
URL: http://jame.iut.ac.ir/article-1-1077-en.html
URL: http://jame.iut.ac.ir/article-1-1077-en.html
Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran. , ahmad_k@iut.ac.ir
Abstract: (2649 Views)
In this study, the effect of Ta/W ratio on the microstructure and stress rupture properties of Ni-based single crystal (SX) superalloy PWA1483 was investigated. For this purpose, single crystal (SX) superalloys with different Ta/W ratios (0.75, 1.0, 1.32 and 1.5 in wt.%) were fabricated. The alloys were directionally solidified by Bridgman method under the same solidification condition at withdrawal velocity of 3 mm/min and thermal gradient of about 7 K/mm followed by standard age hardening heat treatment. Microstructural characterization was performed using optical microscopy (OM) and scanning electron microscopy (SEM). The stress rupture properties were investigated at 982 °C and 248 MPa. The results showed that increasing the Ta/W ratio decreases the size and volume fraction of micro-pores together with the size of γ' precipitates. Hence, the stress rupture life increased. The superalloy with Ta/W ratio of 1.5 showed the minimum size of micro-porosity (18.2 μm) and the maximum stress rupture life (~34 h). The superalloy with Ta/W ratio of 1 showed the most uniform microstructure and creep behavior. It seems that the presence of topologically closed packed (TCP) η-phases is the main reason for stress rupture life decrease in SX superalloy as micro-pores initiated from TCP phases or the TCP/matrix interfaces.
Keywords: Single crystal Ni-based superalloy, PWA1483, Stress rupture properties, Ta/W ratio, TCP phases, Bridgman method.
Type of Study: Research |
Subject:
Characterization and evaluation of engineering materials
Received: 2020/03/30 | Accepted: 2020/09/9 | Published: 2020/12/20
Received: 2020/03/30 | Accepted: 2020/09/9 | Published: 2020/12/20
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