等徑角擠(ji)(ji)扭工藝(Equal channel angular pressing and torsion, ECAPT)是(shi)在(zai)等徑角擠(ji)(ji)壓法(fa)和擠(ji)(ji)扭法(fa)基礎上發展起來的(de)一種(zhong)新(xin)型(xing)大塑性變(bian)形(xing)技術。由(you)于螺旋通道(dao)的(de)存在(zai)，它實現了“一次擠(ji)(ji)壓，兩次剪切”的(de)復合(he)變(bian)形(xing)目的(de)，材料的(de)應變(bian)累積效果(guo)和變(bian)形(xing)均勻程度均可得到明(ming)顯改善。此外(wai)，由(you)于坯(pi)料橫截面(mian)尺寸和形(xing)狀在(zai)每道(dao)次變(bian)形(xing)前后(hou)均不發生變(bian)化(hua)，也為進行多道(dao)次ECAPT變(bian)形(xing)提(ti)供(gong)了可能性。

　　工(gong)程裝備檢測與控制實(shi)驗室(shi)在自行計的等(deng)徑角擠扭模具上進行了A路徑下純鋁(lv)粉末材(cai)料4道次等(deng)徑角擠扭變形(xing)(xing)，制備出組織和性(xing)能優良的塊(kuai)體超(chao)細(xi)晶鋁(lv)。變形(xing)(xing)溫度為(wei)200℃，擠壓速(su)度為(wei)1mm/s。此外(wai)，為(wei)減小變形(xing)(xing)過程中變形(xing)(xing)坯料與模具內壁之(zhi)間(jian)的摩擦，全(quan)程采用MoS2-石墨(mo)復合潤(run)滑劑進行潤(run)滑。變形(xing)(xing)后(hou)坯料整(zheng)體完好(hao)，表面質量(liang)較好(hao)，未出現裂紋、斷裂、破壞(huai)等(deng)現象。

　　坯(pi)料(liao)(liao)變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)(xing)(xing)(xing)的(de)(de)(de)均(jun)(jun)勻(yun)程(cheng)度(du)直接決(jue)定變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)(xing)(xing)(xing)材料(liao)(liao)內(nei)部組織(zhi)結(jie)(jie)構的(de)(de)(de)均(jun)(jun)勻(yun)性(xing)，進(jin)而影(ying)響材料(liao)(liao)的(de)(de)(de)力學性(xing)能和熱穩定性(xing)。為保證(zheng)所獲取的(de)(de)(de)超細晶(jing)材料(liao)(liao)組織(zhi)穩定、性(xing)能優越，并具有(you)工(gong)(gong)業使用價值，應(ying)盡可能地提(ti)高試樣的(de)(de)(de)變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)(xing)(xing)(xing)均(jun)(jun)勻(yun)性(xing)。分(fen)(fen)析(xi)表(biao)明，隨著(zhu)變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)(xing)(xing)(xing)過程(cheng)的(de)(de)(de)繼續(xu)進(jin)行，等效應(ying)變(bian)(bian)(bian)(bian)的(de)(de)(de)分(fen)(fen)布梯(ti)度(du)不斷(duan)減小，坯(pi)料(liao)(liao)的(de)(de)(de)整(zheng)體變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)(xing)(xing)(xing)均(jun)(jun)勻(yun)性(xing)顯著(zhu)提(ti)高。4道(dao)次(ci)變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)(xing)(xing)(xing)結(jie)(jie)束(shu)時，除去靠(kao)近試樣上下(xia)表(biao)面的(de)(de)(de)邊緣部分(fen)(fen)，變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)(xing)(xing)(xing)坯(pi)料(liao)(liao)內(nei)部主要變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)(xing)(xing)(xing)區域內(nei)的(de)(de)(de)等效應(ying)變(bian)(bian)(bian)(bian)分(fen)(fen)布呈現較為均(jun)(jun)勻(yun)的(de)(de)(de)狀態(tai)。這是(shi)由(you)于等徑角擠(ji)(ji)扭工(gong)(gong)藝螺旋(xuan)通道(dao)的(de)(de)(de)存在，坯(pi)料(liao)(liao)每道(dao)次(ci)變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)(xing)(xing)(xing)后，空間位置都相對于前一道(dao)次(ci)旋(xuan)轉了90o，因(yin)此，4道(dao)次(ci)等徑角擠(ji)(ji)扭變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)(xing)(xing)(xing)后，坯(pi)料(liao)(liao)完成了一個(ge)周期360o的(de)(de)(de)旋(xuan)轉，各個(ge)平面均(jun)(jun)同時受到(dao)了剪切變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)(xing)(xing)(xing)作用，變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)(xing)(xing)(xing)均(jun)(jun)勻(yun)程(cheng)度(du)大(da)大(da)提(ti)高。

　　檢(jian)測(ce)表明(ming)，ECAPT工(gong)藝對純鋁粉末材(cai)料(liao)(liao)(liao)(liao)具有(you)極強的(de)(de)致密(mi)效果。材(cai)料(liao)(liao)(liao)(liao)致密(mi)程(cheng)度(du)(du)的(de)(de)改善在(zai)單道次(ci)(ci)ECAPT變(bian)(bian)形(xing)(xing)(xing)后(hou)最為明(ming)顯，坯料(liao)(liao)(liao)(liao)主要(yao)變(bian)(bian)形(xing)(xing)(xing)區內(nei)的(de)(de)大(da)(da)(da)量(liang)微(wei)孔(kong)隙已(yi)基(ji)本消失。隨著變(bian)(bian)形(xing)(xing)(xing)道次(ci)(ci)的(de)(de)增(zeng)加，殘(can)余(yu)孔(kong)隙的(de)(de)數目和大(da)(da)(da)小(xiao)不斷減少(shao)。經(jing)3道次(ci)(ci)ECAPT變(bian)(bian)形(xing)(xing)(xing)后(hou)，坯料(liao)(liao)(liao)(liao)整體已(yi)接近(jin)于(yu)完(wan)全致密(mi)，4道次(ci)(ci)ECAPT變(bian)(bian)形(xing)(xing)(xing)后(hou)，坯料(liao)(liao)(liao)(liao)的(de)(de)相對密(mi)度(du)(du)達到0.99757。材(cai)料(liao)(liao)(liao)(liao)致密(mi)程(cheng)度(du)(du)的(de)(de)提(ti)高(gao)主要(yao)歸因于(yu)較大(da)(da)(da)的(de)(de)塑性(xing)剪切應變(bian)(bian)和較高(gao)的(de)(de)靜(jing)液壓力。在(zai)這兩(liang)個(ge)有(you)利因素的(de)(de)雙重(zhong)作用下，殘(can)余(yu)孔(kong)隙不斷地(di)收縮、減小(xiao)，最終實(shi)現有(you)效焊合。透射電鏡觀察表明(ming)，經(jing)1道次(ci)(ci)ECAPT變(bian)(bian)形(xing)(xing)(xing)后(hou)，材(cai)料(liao)(liao)(liao)(liao)內(nei)部形(xing)(xing)(xing)成大(da)(da)(da)量(liang)位錯胞(bao)；經(jing)4道次(ci)(ci)ECAPT變(bian)(bian)形(xing)(xing)(xing)后(hou)，變(bian)(bian)形(xing)(xing)(xing)組織(zhi)的(de)(de)取(qu)向(xiang)性(xing)消失，胞(bao)壁上的(de)(de)位錯纏結也(ye)被(bei)平直而清晰的(de)(de)新界(jie)面取(qu)代，小(xiao)角(jiao)度(du)(du)晶(jing)界(jie)逐(zhu)漸向(xiang)大(da)(da)(da)角(jiao)度(du)(du)晶(jing)界(jie)轉化，最終在(zai)材(cai)料(liao)(liao)(liao)(liao)內(nei)部形(xing)(xing)(xing)成了大(da)(da)(da)量(liang)尺寸細小(xiao)、分布均勻且(qie)具有(you)大(da)(da)(da)角(jiao)度(du)(du)晶(jing)界(jie)結構的(de)(de)等軸超細晶(jing)組織(zhi)，平均晶(jing)粒尺寸約為600nm。

　　力學(xue)測試(shi)表明，由(you)于晶(jing)粒細化程度(du)(du)的不斷增(zeng)大，材料的強(qiang)度(du)(du)得(de)到提高，經4道次ECAPT變形(xing)后，純鋁的抗拉強(qiang)度(du)(du)高達123.3MPa。顯微(wei)硬(ying)度(du)(du)也隨(sui)著ECAPT變形(xing)累積應(ying)變的增(zeng)加而增(zeng)加，1道次變形(xing)后增(zeng)幅最(zui)為(wei)明顯。隨(sui)著擠壓道次的增(zeng)加，試(shi)樣的硬(ying)度(du)(du)逐漸(jian)趨(qu)于穩定。當ECAPT變形(xing)至4道次時，顯微(wei)硬(ying)度(du)(du)約為(wei)48.5HV。