(1. 徐州工程學(xué)院 機(jī)電工程學(xué)院，徐州 221111；
2. 江蘇省大型工程裝備檢測(cè)與控制重點(diǎn)建設(shè)實(shí)驗(yàn)室，徐州 221111；
3. 合肥工業(yè)大學(xué) 材料科學(xué)與工程學(xué)院，合肥 230009)
摘 要: 采用數(shù)值模擬和實(shí)驗(yàn)分析方法，對(duì)200 ℃條件下純鋁粉末材料1~4道次A路徑等徑角擠扭(ECAPT)變形致密行為、晶粒細(xì)化機(jī)制以及組織和性能演變規(guī)律進(jìn)行研究，制備出組織和性能優(yōu)良的塊體超細(xì)晶鋁。結(jié)果表明：隨變形道次的增加，材料內(nèi)部所累積的應(yīng)變量不斷增大，出現(xiàn)了加工硬化現(xiàn)象，擠壓載荷峰值不斷上升。ECAPT工藝有效提高了變形材料內(nèi)部的靜水壓力，使坯料整體致密程度和變形均勻性得到明顯改善。純鋁組織發(fā)生了連續(xù)動(dòng)態(tài)再結(jié)晶，晶粒在不斷被細(xì)化的同時(shí)，其取向差進(jìn)一步增大，最終在材料內(nèi)部形成了細(xì)小、均勻且被大角度晶界包圍的等軸再結(jié)晶組織。4道次ECAPT變形后，組織平均晶粒尺寸約為600 nm，抗拉強(qiáng)度達(dá)到123.3 MPa。
關(guān)鍵字: 超細(xì)晶材料；等徑角擠扭；多道次變形；組織；性能
（1. School of Mechanical and Electrical Engineering, Xuzhou Institute of Technology, Xuzhou 221111, China;
2. Jiangsu Key Laboratory of Large Engineering Equipment Detection and Control, Xuzhou 221111, China;
3. School of Materials Science and Technology, Hefei University of Technology, Hefei 230009, China）
Abstract:The deformation and densification behaviors of pure Al powders during 1-4 passes equal channel angular pressing and torsion (ECAPT) under route A at 200 ℃ were investigated using numerical simulation and experiment investigation. In addition, both grain refinement mechanism and the evolution of microstructure and mechanical properties were deeply discussed. The bulk ultrafine-grained pure aluminum with fine microstructure and enhanced mechanical properties was fabricated. The results show that with the increasing pass number of ECAPT, the imposed strain increases. Due to the work hardening, the peak load also increases. As the hydrostatic pressure increases under multi-pass ECAPT, residual porosities in the powder consolidates are effectively shrunk and closed, which contributes to the improvement of deformation uniformity and density of the compacts. During ECAPT process, continuous dynamic recrystallization occurs. As the number of ECAPT passes increases, grains are further refined and mechanical properties are largely enhanced. After 4 passes of ECAPT, the microstructure consists of homogeneous ultrafine grains of 600 nm in size and equiaxed in shape with high angle grain boundaries. Moreover, the tensile strength reaches 123.3 MPa.
Key words: ultrafine grained material (UFG); equal channel angular pressing and torsion (ECAPT); multi-pass deformation; microstructure; property
