BEHAVIOR OF LATTICE DEFECTS IN MICROSTRUCTURE-CONTROLLED INTERMETALLICS

微观结构控制金属间化合物中晶格缺陷的行为

基本信息

批准号：
06402050
负责人：
NEMOTO Minoru
金额：
$ 22.85万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1996
项目状态：
已结题

项目摘要

Transmission electron microscope (TEM) investigations have been performed to investigate the characteristic features of phase decomposition and of interaction between dislocations and precipitates in L1_2-based, B2-based and T1_0-based intermetallics. Lattice site occupation and diffusivity in Ni_3Al and NiAl are measured by using an analytical electron microscope. A wide variation of microstructures including spinodal decomposition, zone formation, coherent and incoherent precipitation can be obtained depending on the chemical compositions and aging temperatures. The crystal anisotropy and the deviation from the stoichiometric composition play important roles in the microstructure and the strength variation during aging. One of the most typical features of the precipitation in intermetallics is the precipitation of disordered phases in the ordered matrices. L1_2-ordered Ni_3Al and Co_3 Ti harden appreciably by fine precipitates of coherent fcc disordered gamma upon aging after quenchi … More ng from solution annealing temperature. In these alloys superdislocations are effectively attracted to the disordered particles and extend their widths in the precipitates. The creep strengths of these alloys increase appreciably. A typical example of dislocation bypassing leaving loops surrounding hard precipitates has been observed in Ni_3Al and TiAl containing fine dispersion of carbides. TEM examination of phase decomposition and deformation induced dislocations in NiAl (B2)-Ni_2AlTi (L2_1) and NiTi (B2)-Ni_2AlTi (L2_1) pseudobinary systems have revealed that the glide dislocations are of a <100> type and shear the H-phase at the underaged state but by pass at the overaged state. In the underaged superdislocation pairs are formed by the deformation at room temperature. The lattice misfit between the Ni_2AlHf precipitate and the NiAl matrix is about four times as large as that of NiAl-Ni_2AlTi system. The high temperature strength as well as creep strength increase appreciably by the precipitation of fine Ni_2AlHf phase. TEM observations suggest that the attractive interactions for dislocations at the particle/matrix interfaces plays an important role to increase the high temperature strength of NiAl-based alloys. When intermetallic compounds precipitate in intermetallics, strengthening is dependent on the crystal structures of precipitates, Burgers vectors of glide dislocations and antiphase boundary energies formed during deformation. Less

已经进行了透射电子显微镜（TEM）投资，以研究相位分解的特征以及基于L1_2的基于L1_2的基于B2，基于T1_0的基于T1_0的金属中的脱位和沉淀之间的相互作用。通过使用分析电子显微镜测量Ni_3Al和NIAL的晶格位点占用和难度。可以根据化学成分和衰老温度来获得广泛的微观结构变化，包括旋律分解，区域形成，相干和不连贯的降水。晶体各向异性和偏离化学计量组成在微观结构和衰老过程中的强度变化中起着重要作用。金属间降水的最典型特征之一是有序物品中无序相位的沉淀。 L1_2订购的ni_3al和co_3 ti硬化在鸡蛋后衰老后相干FCC无序伽马的精细精确度……从溶液退火温度中更多地NG。在这些合金中，超级分泌有效地吸引了无序颗粒，并在精确的情况下扩展了其宽度。这些合金的蠕变强度增强了。在含碳化物的精细分散体的Ni_3al和TiAL中观察到了绕过艰难精确度的围绕艰难精确度的围绕艰难精确度的脱位的典型例子。对NIAL（B2）-NI_2ALTI（L2_1）和NITI（B2）-NI_2ALTI（L2_1）伪近似系统的相位分解和变形的TEM检查已表明，滑动脱位是A型<100>类型的h-phase，但通过未经遍及的状态进行了过度的h-phase。在未定的超级固定对中，由室温下的变形形成。 Ni_2AlHF沉淀和NiAL矩阵之间的晶格不合格大约是NIAL-NI_2ALTI系统的晶格。高温强度以及蠕变强度的提高，其精度是良好的Ni_2AlHF相。 TEM观察表明，在粒子/基质接口处的脱位的有吸引力的相互作用在提高基于NIAL的合金的高温强度方面起着重要作用。当金属间化合物在金属间中珍贵时，增强取决于精度的晶体结构，在变形过程中形成的滑行位错的汉堡向量和反相边界能量。较少的