(1. 華中科技大學(xué) 材料科學(xué)與工程學(xué)院 材料成形與模具技術(shù)國家重點(diǎn)實(shí)驗(yàn)室，武漢 430074；
2. 上海航天設(shè)備制造總廠，上海 200245)
摘 要: 本文對比研究了傳統(tǒng)形變熱處理(TMT)與基于脈沖電磁場作用的形變熱處理(TMTP)，后者工藝路徑為固溶淬火-預(yù)拉伸-不發(fā)生形變的脈沖電磁場作用-人工時效。在脈沖電磁場作用過程中，通過模具壓板的位移約束以保證試樣不發(fā)生塑性變形。結(jié)果表明：兩種形變熱處理都能顯著提升退火態(tài)試樣的屈服強(qiáng)度，其中TMTP條件下的屈服強(qiáng)度提升幅度更大，達(dá)254.3%。同時，TMTP工藝下試樣的伸長率略大于TMT工藝下試樣的伸長率。透射電鏡結(jié)果表明，致密分布的析出相保證了兩種形變熱處理試樣的強(qiáng)度。掃描電鏡分析表明，TMT試樣斷口形貌為典型的沿晶斷裂模式，能觀察到少量的韌窩。TMTP試樣斷口也是沿晶斷裂模式，但是韌窩數(shù)量較多。通過晶間析出相與晶界強(qiáng)度之間關(guān)系揭示了TMTP試樣塑性提高的機(jī)理。
關(guān)鍵字: 鋁鋰合金；形變熱處理；脈沖電磁場；晶界析出相；韌窩
（1. State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China;
2. Shanghai Aerospace Equipments Manufacturer, Shanghai 200245, China）
Abstract:The thermomechanical treatment (TMT) and thermomechanical treatment combined with pulsed electromagnetic field (TMTP) were carried out. The latter process is solution treatment and quench, following by pre-stretching, pulsed electromagnetic field treatment without deformation, and artificial aging. During the pulsed electromagnetic field treatment, the displacement constraint of the die plate is used to ensure that no plastic deformation occurs in the specimen. The results show that the two thermomechanical treatment processes can significantly increase the yield strength of the as-annealed specimens, and the increment of yield strength of the specimen under TMTP condition is greater, which reaches 254.3%. At the same time, the elongation of the TMTP specimen is slightly larger than the TMT one. TEM results show that the densely distributed precipitates ensure the strength of the specimens under two TMT conditions. SEM results show that the fracture morphology of the TMT specimen is typical intergranular fracture combined with a small number of dimples, while the TMTP one is intergranular fracture combined with more dimples. Through the relationship between the grain boundary precipitates and the strength of the grain boundary, the mechanism of the plasticity improvement for TMTP specimen was revealed.
Key words: Al-Li alloy; thermomechanical treatment; pulse electromagnetic field; grain boundary precipitates; dimples
