简论贝氏体相变的形核与长大--复康沫狂教授等

指出康沫狂教授文中的一些疑点,主要为：缺乏产生贫,富溶质区的所谓“类spinodal分解”所应具有的理论基础;没有缺陷浓度的计算,以论证偏聚量和缺陷偏聚的实验证据;以及预贝氏体相变尚属疑问。近来高分辨透射电镜实验已证明：贝氏体以相界面台阶扩散长大。作者强调贝氏体相变以扩散机制形核和长大。     

Thermodynamic prediction of M_s in Fe-Mn-Si shape memory alloys associated with fcc(γ)→hcp(ε) martensitic transformation

By means of X-ray diffraction profile analysis of three different composition Fe-Mn-Si alloys, the relationship between stacking fault probability P_(sf) with the concentrations of constituents in alloys, 1/P_(sf)=540.05 23.70×Mn wt％-138.74×Si wt％, was determined. According to the nucleation mechanism by stacking fault in this alloy,the equation between critical driving force ΔG_c and P_(sf), ΔG_c=67.487 0.1775/P_(sf)(J/mol), was made. Therefore,the relationship between critical driving force and compositions was established. Associated with the thermodynamic calculation, the M_s of fcc(γ)→hcp(ε) martensitic transformation in any suitable composition Fe-Mn-Si shape memory alloys can be predicted and results seem reasonable as compared with some experimental data.     

自主创新发展超高强度钢

经总结有关钢的显微组织与力学性能之间的关系,以及超高强度钢发展历史的文献,作出超高强度组织、成分和热处理设计.含＜0.5wt%C,(1～2)%Si,低Mn(Ni)及碳化物形成元素的钢,如0.48C-1.19Mn-1.18Si-0.95Ni-0.2Nb-0.2Mo(wt%)钢,经淬火-碳分配-回火(Q-P-T)新热处理工艺,具抗拉强度>2000MPa,并总伸长率＞10%的性能,且价格低廉.含较低碳的Q-P-T钢也显示良好的综合性能.     

条状马氏体形态对钢力学性质的影响

总结了有关条状马氏体形态对钢力学性质（主要为强度）影响的文献。由于马氏体束比领域小很多,且也具有高角度位向差界面,一般束宽为决定条状马氏体强韧性的主要因素。但当马氏体条宽在几十nm级时,条宽将对钢的强度和韧性作更大贡献。     

Self-energy and interaction energy of stacking fault in fcc metals calculated by embedded-atom method

The stacking fault energies of five fcc metals (Cu, Ag, Au, Ni and Al) with various quan-tivalences have been calculated by embedded-atom method (EAM). It indicated that the stacking fault energy is mainly determined by the metallic bond-energy and the lattice constant. Thus, monovalent fcc metals should have different stacking fault energies, contrary to Attree's conclusion. The interaction energy between stacking faults one I 111 I layer apart in a fcc metal is found to be 1/40-1/250 of its self-energy, while it becomes zero when the two stacking faults are two layers apart. The twin energy is just half of the energy of intrinsic stacking fault energy without the consideration of lattice relaxation and the energy of a single intrinsic stacking fault is almost the same as that of extrinsic stacking fault, which are consistent with the results from the calculation of Lennard-Jones force between atoms, but differ from Attree's result.     

Electronic structure of FCC phase in Fe-Mn-Si based shape memory alloys and its stability

The relationship between the electronic structure of FCC phase in Fe-Mn-Si alloy and its stability has been studied by using the discrete variational method based on the first principle. The reason why Mn and Si elements have different influences on the stacking fault energy may be related to the electron concentration ( e/a). Si reduces the hole number of 3d band while Mn is rather complicated . The binding energy has been calculated and the experimental results that martensite start temperature (Ms) varies with Si and Mn are explained. When the external stress is exerted in three directions, the electronic structure, the total density of states, the energy gap at Fermi energy level( EF) and the energy degeneracy will change into other states. When the different external stresses are exerted in one direction, 3d or 4s orbital occupations of the central atom decrease, the partial density of states seems to be thinner and its peak increases at EF, the bond orbit shrinks in the direction of the external st     

马氏体相变和贝氏体相变研究十年及其展望

综述作者十年来在马氏体相变和贝氏体相变研究成果中一些有关联的部分,包括铁基合金中马氏体相变热力学,郎道理论在热弹性合金中的应用,贝氏体相变热力学,奥氏体强化对马氏体和贝氏体相变的影响,以及马氏体与基体和贝氏体与基体之间的相界面形态及两者的惯习面,并提出展望。     

仪表用新材料—形状记忆合金

简述马氏体相变中的热弹性、伪弹性和形状记忆效应、概略介绍形状记忆合金的条件及其特性;举例说明形状记忆合金在工业上的应用,包括在控温仪表中的一些应用。最后根据目前的认识,阐明形状记忆效应的机制。