Al－Li合金的锯齿屈服现象

THE PHENOMENA OF SERRATED YELDING IN Al-Li ALLOY

研究了一种８０９０型Ａｌ－Ｌｉ合金在室温拉伸变形时的锯齿屈服类型、特征以及相关影响因素，实验结果表明：在一定条件下拉伸变形时，可出现Ａ，Ｂ，Ｃ三类锯齿，其中Ｂ型锯齿常叠加在Ａ型锯齿上构成Ａ＋Ｂ型复合锯齿屈服；时效抑制Ｂ，Ｃ型锯齿屈服；在４．２×１０－５ｓ－１低应变速率下主要出现Ｃ型锯齿屈服，而在４．２×１０－３ｓ－１高应变速率下只产生Ａ型锯齿屈服；可根据据吕德斯带中位错的动态应变时效机制解释不同类型的锯齿屈服现象。

The serrated yielding phenomena in a 8090 type Al-Li alloy during tensile testingat room temperature have been investigated.Three different types of serrations(termedA, B and C)appeared under the proper conditions。 B type serrations were generallysuperimposed On A type serrations to form combined A+ B type serrations。 At lowstrain rat e=4.2×10-5s-1,C type serrations were mainly observed.At high strainrate e=4. 2× 10-3s-1, only A type serrations were observed.Aging suppressed the appear-ance of B and C types of serrations。The results are explained in terms of the strain aging ofmoving dislocations in Luders band front during tensile deformations。