中间形变热处理对2A97铝锂合金厚板组织和性能的影响

Effect of ITMT on Microstructure and Properties of 2A97 Al-Li Alloy Plate

利用拉伸机和疲劳试验机对不同变形量(0%、20%和25%)温压(260℃)后2A97-T84合金厚板的强度及断裂韧性进行了测量,采用金相显微镜、SEM和TEM对微观组织及断口进行了观察。结果表明:随变形量增大,合金的强度和伸长率均先增加后减小,20%变形量合金的σ_(b)、σ_(02)、δ分别为543、436 MPa和5.1%。25%变形量合金的σ_(b)、σ_(02)和δ分别为520、430 MPa和3.5%;合金断裂韧性先增大后减小,断裂韧度最大达到18.56 MPa·m^(1/2)。温压使合金再结晶程度增大,但过多的再结晶晶粒使合金断裂韧性下降;温压使合金、二次相碎化,提高合金断裂韧性。变形量为20%时,合金强化相δ’相和T_(1)相数量最多,合金强度得以提高;变形量为25%时,再结晶消耗了大量位错能,造成强化相数量下降,导致合金强度下降。

The strength and fracture toughness of 2A97-T84 alloy plate after warm compaction(260℃) with different deformation amounts(0%,20% and 25%)were measured by tensile machine and fatigue testing machine. The microstructure and fracture were observed by metallographic microscope, SEM and TEM. The results show that the strength and elongation of the alloy increase first and then decrease with the increase of deformation amount. The σ;, σ;, δof 20% deformed alloys are 543, 436 MPa and 5.1%, respectively. When the amount of deformation is 25%, the σ_(b)、σ_(02) and δ of the alloy are 520,430 MPa and 3.5%, respectively. The fracture toughness of the alloy first increases and then decreases, the maximum fracture toughness reaches 18.56 MPa·m^(1/2). The degree of recrystallization is increased by the warm-pressing, and excessive recrystallized grains deteriorate the fracture toughness of the alloy. The secondary phase is broken by the warm-pressing, and the fracture toughness is improved. When the deformation is 20%, the strengthening phase δ’ phase and T_(1) phase in the alloy are the most, and the strength can be improved. When the deformation is 25%,recrystallization consumes a large number of dislocation’s energy, resulting in a decrease in the number of strengthening phases and a decrease in alloy strength.