Effects of microwave sintering and conventional sintering on microstructures and properties of pure titanium
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摘要: 和熔炼铸造法相比,采用粉末冶金法制备钛材,可以避免引入杂质,提高原料利用率。本文探讨微波烧结与传统烧结对纯钛组织及性能的影响,结果表明,在1200℃保温2 h传统烧结得到等轴α-Ti组织,密度为4.33 g·cm-3,相对密度为96.06%,硬度为HV 260,抗压强度为1309 MPa,断面膨胀率为10.63%,呈典型的解理状脆性断裂;在1200℃保温15 min微波烧结得到等轴的α-Ti与条状β-Ti组织,密度为4.30 g·cm-3,相对密度为95.45%,硬度为HV 311,抗压强度为1175 MPa,断面膨胀率为18.89%,展现出一定的塑性,呈准解理状脆性断裂。Abstract: Compared with the smelting and casting method, powder metallurgy method can avoid impurities and improve the utilization rate of materials. The microstructures and properties of pure titanium prepared by microwave sintering and conventional sintering were studied in this paper. The results show that, the equiaxed grain α-Ti microstructure is acquired by conventional sintering at 1200 ℃ for 2 h, the relative density, density, hardness, compressive strength, and fracture expansion rate are 96.06%, 4.33 g·cm-3, HV 260, 1309 MPa, and 10.63%, respectively. The conventional sintering titanium samples display the typical cleavage brittle fracture. Furthermore, the equiaxed grain α-Ti and strip β-Ti microstructure are acquired by microwave sintering at 1200 ℃ for 15 min, the relative density, density, hardness, compressive strength, and fracture expansion rate are 95.45%, 4.30 g·cm-3, HV 311, 1175 MPa, and 18.89%, respectively. The microwave sintering titanium samples display the quasi-cleavage brittle fracture.
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图 3 1200 ℃传统烧结与微波烧结纯钛试样金相组织:(a)传统烧结腐蚀前;(b)微波烧结腐蚀前;(c)传统烧结腐蚀后;(d)微波烧结腐蚀后
Figure 3. Microstructures of pure titanium samples by different sintering technology at 1200 ℃ (a) conventional sintering before corrosion; (b) microwave sintering before corrosion; (c) conventional sintering after corrosion; (d) microwave sintering after corrosion
图 4 传统烧结与微波烧结纯钛试样硬度分布:(a)垂直于压制方向,靠近压头端由中心到周围的硬度分布;(b)沿压制方向,从压头到底面处的硬度分布
Figure 4. Vickers hardness distribution of pure titanium samples by conventional sintering and microwave sintering: (a) perpendicular to the pressing direction from the center to around; (b) along the pressing direction from the pressure head to bottom
图 6 传统烧结与微波烧结纯钛试样断口形貌:(a)传统烧结(×60);(b)传统烧结(×2000);(c)传统烧结(×5000);(d)微波烧结(×40);(e)微波烧结(×2000);(f)微波烧结(×5000)
Figure 6. Fracture morphology of pure titanium samples by different sintering technology: (a) conventional sintering (×60); (b) conventional sintering (×2000); (c) conventional sintering (×5000); (d) microwave sintering (×40); (e) microwave sintering (×2000); (f) microwave sintering (×5000)
表 1 纯Ti粉化学成分(质量分数)
Table 1. Chemical composition of pure Ti powders
% Fe Si Mg Mn O C N H Ti 其他 0.06 0.02 0.02 0.02 0.30 0.02 0.05 0.04 余量 0.05 表 2 不同烧结方式制备纯钛的相对密度
Table 2. Relative density of pure titanium samples by different sintering technology
试样编号 相对密度/% 密度/(g·cm-3) 生坯 75.00 3.3825 微波烧结(1200 ℃,15 min) 95.45 4.3048 传统烧结(1200 ℃,2 h) 96.06 4.3323 -
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