金属间化合物TiAl(W,Si)合金的蠕变行为和机制

 研究了 Ti-47Al-2 W-0.5 Si合金在 650～ 750℃区间的蠕变行为和变形机制。结果表明,合金 650℃蠕变寿命与施加应力之间符合线性的双对数关系,可用表达式 lg^t_f=10 lg^R+30来描述。蠕变寿命与最小蠕变速率之间满足 Monkman-Grant关系的修正式。合金的比蠕变强度与抗热腐蚀镍基高温合金 K438G相当。在700℃变载荷下蠕变时具有与恒载荷下蠕变相类似的特征。 800℃长期时效粗化合金组织,降低蠕变寿命。位错滑移和形变孪生是合金蠕变的主要变形机制。

CREEP BEHAVIOR AND MECHANISMS OF INTERMETALLIC TiAl(W,Si) ALLOY

Creep behavior and mechanisms of Ti-47Al-2W-0.5Si cast alloy have been investigated. The results show that the creep rupture time at 650℃ decreases rapidly with the increasing of applied stress, and can be expressed by the formula lg^t_f=10 lg^R+30. The creep rupture time and minimum creep rate fit a linear double-logarithmic relationship, and can be described with the revision of Monkman-Grant relationship. Its creep strength is comparable to the density-corrected strength of nickel-based corrosion-resistant superalloy K438G. Step-like various load creep has similar deformation characteristics compared with constant-load creep. Long period aging at 800℃ coarsens the lamellar structure, and subsequently lowers the creep rupture life. Dislocation gliding and deformation twinning are attributed to the dominant creep mechanisms.