HSU Shuen
,
YANG Sycherng
,
HON Weipirn
,
WANG Chienyi LEE Tsangsheau (Chung-Shan Institute of Science and Technology
,
Lung-Tan
,
Taiwan
,
China) HSU Ichung(National Taiwan University
,
Taipei
,
Taiwan
,
China) CHIN Stephen
,
ANTON Donald L.(United Technologies Research Center
,
East Hartford. CT
,
USA)
金属学报(英文版)
The compressive and tensile strain rate sensitivities of polycrystalline and single crystal NiAl have been evaluated at 877 ℃ which is well above DBTT. Samples were prepared to specific sizes by hot press consolidation of appropriate powder sizes and minimizing past consolidation thermal exposures. NiAl single crystals were grown in the [100]orientation using a modified Bridgeman technique. The yield and tensile strength of polycrystalline NiAl as a function of grain size generally follows a Hall-Petch type relationship . A tensile strain rate effect was found at strain rate of 1 to 10-4 sec-1. The strain rate sensitivity coefficient, m,in the equation of σ = Kε is in the range of 0. 10 to 0. 13. The highest strain rate (1 sec-1) resulted in significantly higher strengths and little or no observed ductility. Compressive strain rate testing al strain rate of 10-5to 10-2 sec-1 and at temperature of 1050°to 1250°K was conducted both for polycrystalline and for single crystal NiAl. The calculated stress exponents and the activation energy for creep were compared with the reference data.
关键词:
:strain rate sensitivity polycrystalline NiAl
,
null
XU Zuyao(T.Y.Hsu) PAN Mu Shanghai Jiaotong University
,
Shanghai
,
China Correspondent:XU Zuyao(T.Y.Hsu) Professor
,
Department of Materials Science
,
Shanghai Jiaotong University
,
Shanghai
,
China
金属学报(英文版)
A Central Atom Model is introduced and the LFG and Hsu models are modified in order to evaluate the driving force for the martensitic transformation in Fe-Mn-C and Fe-Ni-C al- loys.The results show that the relationship between the driving force and the yield strength of austenite at Ms temperature,σ_(0.2)~γ/M_s,fits Hsu's formula;ΔG~=2.1σ_(0.2)~γ/M_s+907 J/mol.The M_s temperatures of Fe-Mn-C and Fe-Ni-C alloys are also calculated.The calculated results are in good agreement with experimental values.
关键词:
Fe-Mn-C alloy
,
null
,
null
