【摘要】 研究了Ｔｉ－６．５Ａｌ－３．５Ｍｏ－１．５Ｚｒ－０．３Ｓｉ合金细观结构对裂纹扩展特性的影响。发现当△Ｋ值小于ｄａ／ｄＮ－△Ｋ曲线上转折点处△Ｋ值时，合金出现解理断裂，表明转折点是解理断裂向条纹机制断裂的过渡；大量试验又进而证明，解理断裂与裂尖塑性区大小和裂纹穿过的晶粒或晶域尺寸有关。由此，作者提出了钛合金在裂纹扩展过程中形成解理断裂的一种新的断裂机制。更多还原

【Abstract】 his paper studied the relation of microstructure to crack propagation in Ti-6.5Al-3.5Mo-1.52r-0.35t alloy. It is found that when △K is less than the value of break point on curves da/dN-△K, cleavage fracture was produced,obviously, this point is the break from cleavage to striation fracture. Experiment shows that the formation of cleavage is related to the plasticity zone at crack-tip and the size of grain or colony. When △K is less than the value of curve break,the plasticity at crack-tip is smaller than the size of grain or colony in flout of crack,therefore,the plasticity at crack-tip concentrated wholly in one grain or one colony, and produced three dimensional tension stress, so that the plasticity inside grain was exhausted and brittle cleavage was formed. Inversely,because of cooperative action of grain boundary,three dimensional tension stress inside grain was decreased and the mechanism changes from cleavage to striation.更多还原