(1. 中南大學 粉末冶金國家重點實驗室，長沙 410083； 2. 株州硬質(zhì)合金集團有限公司 硬質(zhì)合金國家重點實驗室，株洲 412000； 3. 株洲硬質(zhì)合金集團有限公司 硬質(zhì)材料研發(fā)中心，株洲 412000)
摘 要: 為了改善WC基鋼結硬質(zhì)合金性能，以熱力學計算為基礎，探索Ni3Al添加量對WC-Fe(Cr, Mo)鋼結硬質(zhì)合金組織與性能的影響。采用粉末冶金方法，以添加Ni3Al預合金粉的方式添加Al，通過液相燒結制得不同Ni3Al含量(0，0.5%，1.0%，1.4%，質(zhì)量分數(shù))的WC-50%(Fe-Ni-Al-Cr-Mo)合金樣品。采用差示掃描量熱分析(DSC)、X射線衍射儀(XRD)、掃描電子顯微鏡(SEM)和金相顯微鏡分別對合金的液相溫度點、相組成和顯微組織進行了檢測分析，并討論了合金物理力學性能和磁性能的變化規(guī)律。結果表明：粘結相主要由γ-α+β′三相構成，且隨著Ni3Al含量的增加，Ni元素可以穩(wěn)定奧氏體，粘結相中γ-Fe含量增加，1250 ℃時，F(xiàn)e-Ni-Al粘結相從液相中析出γ-Fe相的形核驅(qū)動力增大，使得粘結相的晶粒細化，粘結相中析出的NiAl相增多；合金硬質(zhì)相主要為WC和Fe3W3C，WC沿晶界偏聚；γ-Fe含量增多，固溶了更多C元素，使Fe3W3C的含量隨Ni3Al含量增加而減少；WC晶粒細化，分布更為彌散。在上述因素共同影響下，合金密度略有降低，粘結相的磁飽和強度下降，矯頑磁力上升；硬度上升，抗彎強度先下降后上升，并在添加Ni3Al含量為1.4%時，硬度和抗彎強度達到最大值。
關鍵字: WC基鋼結硬質(zhì)合金；Fe-Ni-Al粘結相；組織；性能
（1. State Key Laboratory for Powder Metallurgy, Central South University, Changsha 410083, China; 2. State Key Laboratory of Cemented Carbide, Zhuzhou Cemented Carbide Group Co., Ltd., Zhuzhou 412000, China; 3. Research and Development Center of Hard-metal, Zhuzhou Cemented Carbide Group Co., Ltd., Zhuzhou 412000, China）
Abstract:In order to improve the performance of WC based steel bonded carbide, the effects of Ni3Al content on microstructure and properties of WC-Fe(Cr, Mo) steel bonded carbide were explored based on thermodynamic calculation. The alloys with different Ni3Al contents (0, 0.5%, 1.0%, 1.4%, mass fraction) were prepared by liquid phase sintering method through adding Al with the form of Ni3Al prealloyed powders. The liquidus temperature, phase composition and microstructure of alloys were analyzed by the differential scanning calorimetry (DSC), X-ray diffractometer (XRD), scanning electron microscope (SEM) and metalloscope, respectively. The effects of Ni3Al content on the mechanical and magnetic properties of alloys were investigated. The results show that, with the increase of Ni3Al content, γ-Fe content increase, due to the improved stabilities of austenite through the solution of Ni element. The driving force for the nucleation of the γ-binder precipitating from liquid phase at 1250 ℃ increases, which refines the grains, NiAl precipitation in the binder phase increases. The hard phases are mainly WC and Fe3W3C, with the increase of Ni3Al content, more C element dissolves in γ-Fe binder phase, which leads to a less precipitation of Fe3W3C, refined WC grains are distributed more dispersedly. Above all, with the increase of Ni3Al content, the density of alloys decreases slightly. The magnetic saturation of binder phase decreases while coercive force increases. The hardness of alloys raises while the transverse rupture strength of alloys first decreases, then increases. Both the hardness and transverse rupture strength reach maximum value when the Ni3Al content is 1.4%.
Key words: WC based steel bonded carbide; Fe-Ni-Al binder phase; microstructure; property
