摘要
用热重法研究了Ti ( 50± 2 )Al及Ti 4 8Al ( 1 ,4 )Cr等铸态TiAl基合金于 80 0℃静止空气中的循环氧化行为·结果表明 ,低Cr合金化TiAl的抗氧化性比二元TiAl的差·原因在于适量的Cr促进了TiAl表层原子的扩散 ,从而使氧化反应加速·因循环氧化而产生的应力疲劳使氧化物间的裂纹过早萌生、扩展并导致氧化层开裂 ,从而在通过致密膜进行固体扩散氧化反应的基础上引入了优先通过裂纹间隙进行气体短路扩散氧化的反应机制 ,最终使氧化程度加重 ,氧化规律表现为线性规律·氧化表面分层为 :二元TiAl表面呈富Ti/富Al交替的 (TiO2 +Al2 O3 )结构 ,三元TiAl Cr最外层则由纯R TiO2 晶体构成·
Oxidation behaviors of Ti 50Al,Ti 48Al,Ti 52Al,Ti 48Al 1Cr and Ti 48Al 4Cr during 100 thermal cycles from 800?℃ for 1 hour in static air to room temperature for 10 minites were studied by the TGA method. Mass gain (Δ M ) of ternary TiAl Cr is a magnitude larger than that of binary TiAl. Unlike interrupted oxidation of TiAl at the same condition, cyclic oxidation shows linear kinetic law. It is shown that the deterioration in oxidation resistance of the TiAl alloys with increasing the cycling number results from the thermal stresses among TiO 2,Al 2O 3 and TiAl phases,and the micro cracks introduced by the thermal shock,which lead the short way diffusion of oxygen. The typical oxidation stratification of TiAl was identified as the surface TiO 2 layer /the (TiO 2+Al 2O 3) mixture layer with alternate rich Ti or rich Al sub layers/diffusion zone/TiAl matrix.
出处
《东北大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2000年第4期404-407,共4页
Journal of Northeastern University(Natural Science)
基金
国家自然科学基金!( 5 9895 15 0 )
国家"八六三"高技术计划共同资助项目
