标题: 铁铝锰碳, 铁铝锰矽碳和铁铝镍碳合金相变化
Phase Transformations in Fe-Al-Mn-C, Fe-Al-Mn-Si-C and Fe-Al-Ni- C Alloys
作者: 黄志能
Huang, Zhi-Neng
刘增丰
Liu, Zeng-Feng
材料科学与工程学系
关键字: 规律化转变;史宾诺多分解;沃斯田铁;肥粒铁;材料科学;物理;Ordering transition;Spinodal Demposition;Austenite;Ferrite;MATERIALS-SCIENCE;PHYSICS
公开日期: 1996
摘要: The phase transformations in the Fe-8.0Al-31.5Mn-1.05C,
Fe-9Al-30Mn-2.0C, Fe-9.0Al-30.5Mn-(0-2.5)Si-1.2C, Fe-8Al-5Ni-2C,
have been examined by means of OM, STEM and EDS. As a result the
following conclusions have been presented.(1) When the Fe-8.0
Al-31.5Mn-1.05C alloy was solution heat-treated and quenched,
the microstructure was single-phase austenite. After being
aged at 550℃, a γ→γ+κ-phase transition had occurred on
the grain boundaries and twin boundaries. This result is quite
different from that observed by other workers in the Fe-(4.9-11)
wt pct Al-(28.5-34.3) wt pct Mn-(0.50-1.62)wt pct C alloys.
In their studies, they found that when the alloy was aged
at temperatures ranging from 550℃to 650℃, aγ→α+β-Mn, γ→
α+β-Mn+κand γ→ β-Mn reaction occurred on the grain
boundaries.(2) In the as-quenched condition, the microstructure
of Fe-9Al-30Mn-2.0C alloy was a mixture of (γ+κ'-
carbide). When the alloy was aged at temperatures ranging from
550 ℃ to 750 ℃, fine κ'-carbides existing in the as-
quenched austenite matrix grew preferentially along <100>
directions and a γ→γ+κ-phase transition had occurred on the
grain boundaries. When the aging temperature was in the
range from 850℃ to 950℃, both coarse κ' and fine κ'-
carbides could be observed within the austenite matrix . In the
grain boundaries, a γ→ γ+coarse κ-carbide + fine κ-
carbide transition had occurred on the grain boundaries. It
is worthy to note that the κ-phase carbide has L'12-type
structure at 650℃ or below and has an L12 type structure at
750℃ or above. These results are quite different from those
reported by other workers in various Fe-Al-Mn-C alloys.(3) The
effects of Si addition on the as-quenched microstructure of
Fe-9.0Al-30.5Mn-1.2C alloy have been investigated. The
results indicated that Si addition would enhance the κ'-
carbides to precipitate coherently within the austenite
matrix during rapid quenching by spinodal decomposition.
With increasing the Si content to 1.5wt.%, (α+ D03) phases were
also formed on the austenite grain boundaries in addition to
the formation of the κ'-carbides within the austenite
matrix. The D03 phase was formed during quenching by a α→B2→
D03 continuous ordering transition. (4) In the as-quenched
condition, the microstructure of the alloy was austenite phase
containing fineκ'-carbides. Theκ' carbides were formed
during quenching by a spinodal decomposition. When the as-
quenching alloy was aged at 550℃for short times, theκ'-
carbides grew along <100> directions. After prolong aging at
this temperature, aγ→α+B2+κ reaction occurred on the
austenite grain boundary. This result is different from that
observed by Choo and Kim in the same alloy.
URI: http://140.113.39.130/cdrfb3/record/nctu/#NT854058002
http://hdl.handle.net/11536/62464
显示于类别:Thesis