Crack initiation mechanism in lanthanum-doped titanium-zirconium-molybdenum alloy during sintering and rolling

Lanthanum-doped titanium-zirconium-molybdenum (La-TZM) alloy was prepared by powder metallurgy and rolling process. The processing crack and crack initiation mechanisms of La-TZM alloy after sintering, hot rolling and cold rolling were studied by scanning and transmission electron microscopy. The re...

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Bibliographic Details
Published in:Journal of alloys and compounds 2018-05, Vol.745, p.532-537
Main Authors: Hu, Ping, Zhou, Yu-hang, Deng, Jie, Li, Shi-lei, Chen, Wen-jing, Chang, Tian, Hu, Bo-liang, Wang, Kuai-she, Feng, Peng-fa, Volinsky, Alex A.
Format: Article
Language:English
Subjects:
Cleavage
Cold pressing
Cold rolling
Crack initiation
Crack mechanism
Crack propagation
Dislocations
Fracture
Fracture mechanics
Fracture surfaces
Fractures
Hot rolling
Lanthanum
Lanthanum-doped titanium-zirconium-molybdenum alloy
Microstructure
Molybdenum
Powder metallurgy
Scanning electron microscopy
Secondary phase particles
Sintering (powder metallurgy)
Stress concentration
Stress propagation
Tensile stress
Titanium
Titanium base alloys
Transmission electron microscopy
Zirconium
Zirconium hydrides
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Summary:Lanthanum-doped titanium-zirconium-molybdenum (La-TZM) alloy was prepared by powder metallurgy and rolling process. The processing crack and crack initiation mechanisms of La-TZM alloy after sintering, hot rolling and cold rolling were studied by scanning and transmission electron microscopy. The results show that the doped La(NO3)3, TiH2 and ZrH2 have finer secondary phase in the La-TZM alloy plate. The fracture mode of sintering billet is inter-granular, but the fracture surface of hot rolling exhibited transgranular cleavage. However, the cold rolling is quasi-cleavage fracture. The secondary phase particles tend to hinder the movement of dislocations causing dislocations pile-up. The resulting tensile stress can accelerate cracks nucleation and growth, and the crack propagation will be deflected by the secondary phase particles. The crack initiation can be avoided by reducing local stress concentration caused by dislocations. •This is the first time to study the crack initiation mechanism of La-TZM alloy.•The aggregated micro-pores at grain boundaries forming cracks during sintering.•The Secondary phase particles and grain boundaries tend to hinder the movement of dislocations.•Cracks are most susceptible to nucleation at micro-pores and secondary phase particles.
ISSN:0925-8388
1873-4669
DOI:10.1016/j.jallcom.2018.02.191