Microstructural evolution and phase transformations of mechanically stirred non-dendritic ZA27 alloy during partial remelting
Chen Ti-jun , Hao Yuan , Sun Jun
Journal of Wuhan University of Technology Materials Science Edition ›› 2004, Vol. 19 ›› Issue (4) : 56 -61.
Microstructural evolution and phase transformations of mechanically stirred non-dendritic ZA27 alloy during partial remelting
The microstructural evolution and phase transformations of mechanically stirred non-dendritic ZA27 alloy during partial remelting were studied by using scanning electron microscopy and X-ray diffraction technique. The partial remelting temperature was 460°C and lower than the stirring temperature of 465°C. So the microstructure with globular grains needed for semi-solid forming can not be obtained and the starting primary nondendritic grains change in turn to connect non-dendritic grains, long chain-like structures and finally to coarsen connect grains. However, the small near-equiaxed grains between the primary non-dendritic grains are evolved into small globular grains gradually, some of which are also attached to the primary non-dendritic grains during the subsequent heating. The X-ray diffraction results show that a series of phase transformations, α+ν+ε→β, ν+β→L, β→α′+L, α+η+ɛ→α′ and α′→L, occur successively during this process. The main reason why the starting primary non-dendritic grains do not separate into the needed independent globular grains is that the reactions of ν+β→L and α′→L do not occur or occurr incompletely in the layers used to connect the primary nondendritic grains.
ZA27 alloy / partial remelting / semi-solid forming / microstructure evolution / phase transformation
| [1] |
|
| [2] |
|
| [3] |
|
| [4] |
|
| [5] |
|
| [6] |
|
| [7] |
|
| [8] |
|
| [9] |
|
| [10] |
|
| [11] |
|
| [12] |
|
| [13] |
|
| [14] |
|
| [15] |
|
| [16] |
|
| [17] |
|
/
| 〈 |
|
〉 |
PDF
