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Effects of chromium addition on fatigue crack growth behavior of titanium aluminides

Ong, Wei Rex (2008) Effects of chromium addition on fatigue crack growth behavior of titanium aluminides. Masters thesis, Universiti Teknologi Malaysia, Faculty of Mechanical Engineering.

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Abstract

The microstructure and fatigue crack growth behavior of various compositions of Ti-Al based intermatellics, Ti-48Al (at%), and the ternary alloys, Ti- 48Al-2Cr, Ti-48Al-4Cr and Ti-48Al-8Cr (at%) have been studied. The fatigue crack growth tests were performed on center-cracked-tension M(T) specimens at room temperature in laboratory air, subjected to a constant applied stress range 100MPa with a load ratio of minimum to maximum level, R = 0.1. It was found that the threshold of stress intensity factor range of Ti-48Al, Ti-48Al-2Cr, Ti-48Al-4Cr and Ti-48Al-8Cr are 12.0MPa v m, 9.0MPa v m, 8.0MPa v m and 4.5MPa v m respectively. The threshold of stress intensity factor range decreased with the increasing percentage of chromium added to Ti-48Al. The results also show that Ti- 48Al-2Cr has the highest fatigue crack resistance followed by Ti-48Al, Ti-48Al-4Cr and Ti48Al-8Cr. Field Emission Scanning Electron Microscopy (FESEM) technique was employed to investigate the fractography of each specimen after fatigue crack growth test. Micro-indentation tests results showed increasing hardness value of Ti- 48Al alloys when the chromium content increased. The microstructures of each type of Ti-48Al alloys were examined using optical and Scanning Electron Microscope (SEM). Finer laths of and plates in lamellar structure have been observed when the amount of chromium added in Ti-48Al increased. The effects of microstructure on fatigue crack growth of Ti-48Al alloys are discussed.

Item Type:Thesis (Masters)
Additional Information:Thesis (Sarjana Kejuruteraan (Mekanikal)) - Universiti Teknologi Malaysia, 2008; Supervisor : Prof. Dr. Esah binti Hamzah
Uncontrolled Keywords:microstructure, fatigue crack growth, chromium
Subjects:T Technology > TJ Mechanical engineering and machinery
Divisions:Mechanical Engineering
ID Code:10064
Deposited By: Ms Zalinda Shuratman
Deposited On:30 Jul 2010 02:35
Last Modified:07 Aug 2012 06:45

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