Effect of Y, Sr, and Nd additions on the microstructure and microfracture mechanism of squeeze-cast AZ91-X magnesium alloys
- Pohang Univ. of Science and Technology (Korea, Republic of). Center for Advanced Aerospace Materials
- Yonsei Univ., Seoul (Korea, Republic of). Dept. of Metallurgical Engineering
This study aims to investigate the effects of Y, Sr, and Nd additions on the microstructure and microfracture mechanism of the four squeeze-cast magnesium alloys based on the commercial AZ91 alloy. Microstructural observation, in situ fracture tests, fractographic observation were conducted on the alloys to clarify the microfracture process. Microstructural analyses indicated that grain refinement could be achieved by small additions of alloying elements, although the discontinuously precipitated Mg{sub 17}Al{sub 12} phases still existed on grain boundaries. From in situ fracture observation of an AZ91-Sr alloy, it was seen that coarse needle-shaped compound particles and Mg{sub 17}Al{sub 12} phases located on the grain boundary provided easy intergranular fracture sites under low stress intensity factor levels, resulting in the drop in toughness. On the other hand, the AZ91-Y and AZ91-Nd alloys showed improved fracture toughness, since deformation and fracture paths proceeded into grains rather than to grain boundaries, as the planar slip bands and twinnings actively developed inside the grains. These findings suggested, on the basis of the well-developed planar slip bands and twinnings, that the small addition of Y or Nd was very effective in improving fracture toughness.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 616498
- Journal Information:
- Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Vol. 29, Issue 4; Other Information: PBD: Apr 1998
- Country of Publication:
- United States
- Language:
- English
Similar Records
Microstructure Evolution and Mechanical Properties of the AZ91 Magnesium Alloy with Sr and Ti Additions in the As-Cast and As-Aged Conditions
Effect of in-situ (TiC-TiB2) reinforcement on aging and mechanical behavior of AZ91 magnesium matrix composite