(1. 華南理工大學(xué) 國家金屬材料近凈成形工程技術(shù)研究中心，廣州 510641；
2. 華南理工大學(xué) 金屬材料高效近凈成形技術(shù)與裝備教育部重點(diǎn)實(shí)驗(yàn)室，廣州 510640)
摘 要: 利用放電等離子燒結(jié)(SPS)技術(shù)對(duì)具有相同理論密度的燒結(jié)態(tài)93W-4.9Ni-2.1Fe和95W-2.8Ni-1.2Fe-1Al2O3高密度鎢合金進(jìn)行循環(huán)熱處理，并通過光學(xué)顯微鏡、SEM、TEM、EDS和三點(diǎn)彎曲實(shí)驗(yàn)分析循環(huán)熱處理對(duì)兩種合金顯微組織和力學(xué)性能的影響規(guī)律。結(jié)果表明：隨著SPS循環(huán)熱處理次數(shù)的增加，93W-4.9Ni-2.1Fe合金在平均W晶粒尺寸未發(fā)生明顯變化的同時(shí)，其粘結(jié)相中的W含量和位錯(cuò)密度不斷升高，合金得到了固溶強(qiáng)化與位錯(cuò)強(qiáng)化，合金的硬度、抗彎強(qiáng)度、斷裂撓度等性能相應(yīng)提高；而對(duì)于95W-2.8Ni-1.2Fe-1Al2O3合金，由于更高的W含量和Al2O3顆粒的加入，燒結(jié)態(tài)時(shí)具有小得多的平均W晶粒尺寸、更大的W-W連接度和高硬脆特性，且SPS循環(huán)熱處理對(duì)其組織和成分分布的均勻性影響程度相對(duì)較小，其力學(xué)性能雖然隨SPS循環(huán)熱處理次數(shù)的增加也得到了一定程度改善，抗彎強(qiáng)度和斷裂撓度明顯較93W-4.9Ni-2.1Fe合金的低，硬度則明顯高于93W-4.9Ni-2.1Fe合金硬度。但循環(huán)熱處理次數(shù)過多，反而會(huì)降低兩種鎢合金的硬度和斷裂撓度。
關(guān)鍵字: 高密度鎢合金；放電等離子燒結(jié)；循環(huán)熱處理；組織；性能
（1. National Engineering Research Center of Near-Net-Shape Forming for Metallic Materials, South China University of Technology, Guangzhou 510641, China;
2. Key Laboratory of High-efficiency Near-net-shape Forming Technology and Equipments for Metallic Materials, Ministry of Education, South China University of Technology, Guangzhou 510640, China）
Abstract:The effect of cyclic heat-treatment based on spark plasma sintering (SPS) technique on the microstructure and mechanical properties of as-sintered 93W-4.9Ni-2.1Fe and 95W-2.8Ni-1.2Fe-1Al2O3 heavy alloy with the same theoretical density was studied by optical microscopy, SEM, TEM, EDS and three –point bending tests. The results show that with increasing the SPS cycle index, the average W grain size of 93W-4.9Ni-2.1Fe alloy unchanges markedly, while both the tungsten content and dislocation density in matrix tend to increase. As a result, the hardness, bending strength and fracture deflection of the alloy are improved gradually owing to solid solution and dislocation strengthening by the treatment. 95W-2.8Ni-1.2Fe-1Al2O3 alloy, possesses quite less average W grain size, higher W-W contiguity and highly hard and brittle characteristics, because of the higher W content and the addition of Al2O3 particles. Its microstructure and composition distribution are affected in a lower degree by SPS cyclic heat-treatment. Although the mechanical property is improved with increasing the SPS cycle index, the obtained bending strength and fracture deflection are obviously lower those of 93W-4.9Ni-2.1Fe alloy, except quite bigger hardness. However, too many times of cyclic heat treatment induce the decrease of hardness and fracture deflection of the two types of alloys.
Key words: tungsten heavy alloy; spark plasma sintering; cyclic heat-treatment; microstructure; property
