沙宪伟
,
张修睦
,
陈魁英
,
李依依
金属学报
运用ＮｉＡｌ合金的镶嵌原子势，进行了Ｂ２结构ＮｉＡｌ中热诱发马氏体相变的分子动力学模拟，从而研究马氏体形核和长大的微观机理．首先进行了０Ｋ等体积条件下ＮｉＡｌ的相稳定性分析，发现０Ｋ时点阵参数ｃ与ａ之比约为１．３１的ｂｃｔ结构是稳定结构，Ｂ２结构只是一种亚稳结构．在热诱发马氏体相变的模拟过程中，由于ＮｉＡｌ中Ｎｉ原子和Ａｌ原子的振动性质存在着差异，造成了马氏体的不均匀形核．对另两种不同初始构型的系统进行的模拟进一步证实了不均匀形核的存在，并通过计算Ｂ２结构ＮｉＡｌ中Ｎｉ原子和Ａｌ原子的热运动均方位移解释了其原因．模拟中，Ｂ２结构奥氏体经热诱发马氏体相变转变为ｆｃｔＬ１_０结构的马氏体．马氏体在长大过程中内部形成了若干转变孪晶．
关键词:
马氏体相变
,
molecular dynamics simulation
,
embedded atom method
,
NiAl
曾潮流
,
吴维旻
,
郭建亭
金属学报
本文研究了在９５０℃空气中，表面涂Ｎａ_２ＳＯ_４盐膜的条件下，ＮｉＡｌ，ＮｉＡｌ－２０％Ｆｅ及渗铝后的高温热腐蚀行为。在热腐蚀过程中，ＮｉＡｌ合金表面能形成Ａｌ_２Ｏ_３膜，显示出一定的耐蚀性能。但Ａｌ_２Ｏ_３膜易开裂，Ａｌ_２Ｏ_３膜的溶解及开裂会引发合金发生快速热腐蚀；２０％Ｆｅ的加入则使ＮｉＡｌ合金的耐蚀性能显著变差，合金表面不能形成单一的Ａｌ_２Ｏ_３膜；渗铝处理可以明显提高ＮｉＡｌ－２０％Ｆｅ合金的耐蚀性能，且渗铝涂层的耐蚀性能优于ＮｉＡｌ合金，这与铝化物涂层中的Ａｌ含量较高，Ａｌ_２Ｏ_３膜的开裂倾向较小有关。
关键词:
金属间化合物
,
NiAl
,
NiAl-20%Fe
,
aluminide coating
,
Na_2SO_4
,
hot corrosion
XING Zhanping*
,
GUO Jianting
,
HU Zhuangqi
,
AN Geying*Institute of Metal Research
,
Chinese Academy of Sciences
,
Shenyang
,
China * Harbin Institute of Technology
,
Harbin
,
China
金属学报(英文版)
Ni-50at.%A1 matrix composites containing 0 to 20v.% TiB2 particles have been successfully fabricated by HPES technique. The results show that the Vickers hardness at room temperature and the compressive yield strength from room temperature to 1000℃ of the composites increase with increasing volume fraction of the strengthening phase. Especially, the yield strength of NiAl-20TiB2 was approximately twice as high as that of unreinforced NiAl. The ductility of the composites at room temperature is also superior to the monolithic NiAl.
关键词:
intermetallic matrix composite
,
null
,
null
,
null
,
null
LIU Zhiguang+ *
,
GUO Jianting *
,
LI Gusong+
,
HU Zhuangqi++State Key Lab. of RSA
,
Institute of Metal Research
,
Chinese Academy of Sciences
,
Shenyang
,
China * Institute of Metal Research
,
Chinese Academy of Sciences
,
Shenyang
,
China
金属学报(英文版)
Mechanical alloying (MA) of Ni50Al45Ti5 (atomic per cent) is studied by in situ thermal analyses, XRD and metallography. The results showed that the alloying process of Ni50Al45Ti5 is similar to that of Ni50Al50. The addition of 5 at.%Ti prolongs the milling time of alloy prior to the explosive reaction in the alloy. The final product is nanocrystalline β-phase NiAl(Ti) (B2 structure). The addition of 5 at.% Ti shows little effect on the lattice parameter of β-phase.
关键词:
mechanical alloying
,
null
,
null
,
null
Gerhard Sauthoff(Max-Planck-Institut fur Eisenforschung GmbH.
,
D-40074 Dusseldorf
,
Germany)
金属学报(英文版)
Intermetallics for structural applications at high temperatures must show a sufficient high temperature strength which is controlled by creep processes. In the first section the creep behaviour of single-phase intermetallic alloys is overviewed with respect to stress and temperature dependence and effects of composition and microstructure. It is shown in particular that creep deformation is controlled by diffusion. The second section refers to multiphase intermetallic alloys, and both particulate and non-particulate alloys are regarded. Data are presented for single-phase and multiphase alloys based on B2 phases and lesscommon phases and the consequences of diffusion control for alloy design are discussed.
关键词:
:creep
,
null
,
null
,
null
,
null
M. V. Nathal (NASA Lewis Research Center Cleveland OH. USA)
金属学报(英文版)
The purpose of this paper is to review the current state of development of new composite materials for advanced aircraft engines. The advantages and disadvantages of Ti-base.NiAl-base, and MoSi_2-base composites as replacements for today's Ni-base superalloys are discussed from the standpoint of key technical issues. current status, and future directions. Results describing progress in both improved understanding of the mechanisms of deformation and fracture, and improved material performance will be covered.
关键词:
: composites. Ti alloys
,
null
,
null
,
null
,
null
