Formation of face-centered cubic titanium in laser surface re-melted commercially pure titanium plate
来源期刊：JOURNAL OF MATERIALS SCIENCE TECHNOLOG2018年第5期
论文作者：Zhuo Li Xu Cheng Jia Li Huaming Wang
文章页码：767 - 773
摘 要：Micron-scale face-centered cubic titanium phase（named as δ phase） were noticed in the re-melted zone of laser surface re-melted commercially pure titanium plate.The morphology,sub-structure,orientation and distribution of δ phase were investigated by scanning electron microscopy,electron back-scattered diffraction and transmission electron microscopy.Three kind formation processes of δ phase were put forward based on the investigation.The first one is α’→δ transformation which takes place in single α’grains and leads to the orientation relationship {001}δ//{0001}α’< 110 > δ//< 1120 >α’.The second one is β→α’+ δ transformation which takes place at α’/α’interfaces and leads to the orientation relationship{001}δ//110β110 δ//111β.The third one is another kind of β→α’+ δ transformation that takes place at α’/α’interfaces and leads to the orientation relationship111δ//110β< 110 > δ//< 111 < β.It is believed that the transformations of δ phase are stress assistant ones and in the present investigation,the phase transformation stress of β→α’transformation acts as the assistant driving force for the formation of δ phase.
Zhuo Li，Xu Cheng，Jia Li，Huaming Wang
National Engineering Laboratory of Additive Manufacturing for Large Metallic Components,School of Materials Science and Engineering,Beihang University
摘 要：Micron-scale face-centered cubic titanium phase（named as δ phase） were noticed in the re-melted zone of laser surface re-melted commercially pure titanium plate.The morphology,sub-structure,orientation and distribution of δ phase were investigated by scanning electron microscopy,electron back-scattered diffraction and transmission electron microscopy.Three kind formation processes of δ phase were put forward based on the investigation.The first one is α’→δ transformation which takes place in single α’grains and leads to the orientation relationship {001}δ//{0001}α’< 110 > δ//< 1120 >α’.The second one is β→α’+ δ transformation which takes place at α’/α’interfaces and leads to the orientation relationship{001}δ//110β110 δ//111β.The third one is another kind of β→α’+ δ transformation that takes place at α’/α’interfaces and leads to the orientation relationship111δ//110β< 110 > δ//< 111 < β.It is believed that the transformations of δ phase are stress assistant ones and in the present investigation,the phase transformation stress of β→α’transformation acts as the assistant driving force for the formation of δ phase.
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