(湖南大學 材料科學與工程學院，長沙 410082)
摘 要: 通過在原料粉末中配置TiH2粉末的方法將燒結Ti-6Al-4V合金的實際置氫量控制在0~0.69%，系統(tǒng)研究了置氫量對顯微組織演變、相構成、形態(tài)與分布的影響規(guī)律，并借助OM、SEM、EDS、XRD和EBSD開展探究與表征。結果表明：1) 置入0.12%的氫可以使合金獲得近平衡態(tài)顯微組織的燒結時間從3 h減少為2 h。2) 當置氫量逐步增加到0.69%時，α相含量從82.44%急劇減少至15.22%，而β相含量從3.59%增加到50.77%，同時α相的形態(tài)從粗大片狀轉變?yōu)閿嗬m(xù)分布于β相周圍的細片狀，β相的形態(tài)則從斷續(xù)分布于α相間的細條狀轉變?yōu)榘鍓K狀。3) 隨著置氫量的提高，HCPα''''馬氏體的含量從8%左右增加到約25%，并呈局部集中狀分布在α相內；置氫量為0.54%時，針狀δ氫化物開始生成，分布在α和β相內及兩相之間，此時α''''的含量再次降低至8%左右。4) 斜方結構馬氏體α"的含量也隨著置氫量的提高而增加，但是當α"含量達到5%左右后便維持不變，呈細小等軸狀分布于α相內。5) 置氫量對合金中顯微組織構成、α+β片層束及晶粒形態(tài)能夠產(chǎn)生顯著影響。最后，根據(jù)實驗結果對置氫燒結Ti-6Al-4V合金顯微組織的演變機理開展了分析與討論。
關鍵字: 置氫燒結；Ti-6Al-4V；顯微組織；相組成
（College of Materials Science and Engineering, Hunan University, Changsha 410082, China）
Abstract:The real hydrogenation contents were controlled in the range from 0 to 0.69% (mass fraction) by adding TiH2 powders to the raw powders, and the effects of real hydrogenation contents on microstructure evolution and phase composition, morphology and distribution of sintering Ti-6Al-4V alloys were comprehensively investigated. Means of OM, SEM, EDS, XRD and EBSD were used for the exploration and characterization. The results are as the follows: 1) The time for microstructure reaching the near-equilibrium-state reduces from 3 h to 2 h at hydrogenation content of 0.12%. 2) With hydrogenation content increases to 0.69% gradually, the volume fraction of α phase reduces from 82.44% to 15.22% and the volume fraction of β phase increases from 3.59% to 50.77%. Meanwhile, coarse lamellar α phase transforms to fine lamellar α phase distributing around β phase discontinuously, and thin strip β phase distributing between α phases discontinuously transforms to plate β phase. 3) The volume fraction of HCP α′ martensite increases from about 8% to about 25% with the increase of hydrogenation content, which distributes in α phase locally and intensively; Acicular δ hydride generates at 0.54% hydrogenation content, which distributes in α and β phases and between the two phases. Meanwhile, the volume fraction of HCP α'''' martensite reduces to about 8% again. 4) Though the volume fraction of orthorhombic α" martensite increases with the increase of hydrogenation content, it only reaches about 5% and distributes in α phase with small equiaxed shape. 5) The hydrogenation content can also effectively affect the microstructure composition, (α+β) lamellar beam and grain morphology. Finally, the microstructure evolution mechanism of hydrogenated sintering Ti-6Al-4V alloys was analyzed and discussed on the basis of experimental results.
Key words: hydrogenated sintering; Ti-6Al-4V; microstructure; phase composition
