Grinding mechanism and mechanical properties of the in-situ synthesized Al2O3/TiAl composites
Grinding mechanism and mechanical properties of the in-situ synthesized Al2O3/TiAl composites
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原位合成Al2O3/TiAl复合材料的磨削机理及力学性能
DOI：
10.1016/j.ceramint.2019.03.111
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发表时间：
2019-06-15
影响因子：
5.2
通讯作者：
Pan, Fusheng
中科院分区：
文献类型：
--
作者：
Lu, Xiaofang;Li, Jianbo;Pan, Fusheng
通过对预合金 Ti-45Al-7Nb-0.3W 和 TiO2 粉末混合物进行机械铣削，然后采用放电等离子烧结 (SPS) 技术进行烧结，原位合成了 Al2O3/TiAl 复合材料。混合粉末经历了初始破坏性破碎阶段、冷焊包阶段和机械球磨过程中巨石破碎阶段。随着机械球磨时间的增加，粒径明显下降。当球磨时间增加到20 h时，球磨粉末的数均直径（D(1,0)）从75.0 μm迅速减小到约15.5 μm，其分布均匀度（U）下降到0.55。研磨过程中形成了纳米 Al2O3 颗粒。 as-SPSed 压坯主要由 γ-TiAl 相、α(2)-Ti3Al 相和纳米 Al2O3 颗粒组成，这些颗粒倾向于分散在基体的晶界和层状微观结构内部。随着球磨时间从 10 小时增加到 20 小时，Al2O3 的含量从 4.3% 增加到 8.9 vol%。浓度的增加导致Al2O3/TiAl复合材料的维氏硬度增加，达到最大值6.2 GPa。构建了修正的混合规则，可以准确预测复合材料的硬度。随着球磨时间的延长，极限抗压强度（UCS）先增大后减小。当混合粉末球磨15 h时，即TiAl基体中Al2O3的含量为7.6 vol%时，获得最高值1848 MPa。
In-situ synthesis of Al2O3/TiAl composite was carried out by mechanical milling of the pre-alloy Ti-45Al-7Nb-0.3W and TiO2 powder mixture and subsequent sintering by spark plasma sintering (SPS) technique. The mixed powders experienced the initial destructive breakage stage, cold welding package stage and breaking up of boulders stage during mechanical milling. The particle size obviously declined with the mechanical milling time increasing. The number-average diameter (D(1,0)) of as-milled powders rapidly reduced from 75.0 mu m to about 15.5 mu m, and its distribution uniformity (U) decreased to 0.55 when milling time increased to 20 h. Nano Al2O3 particles had been formed during milling. The as-SPSed compacts were mainly composed of gamma-TiAl phases, alpha(2)-Ti3Al phases and nano-Al2O3 particles that tended to disperse both on the grain boundaries and inside the lamellar microstructure of the matrix. The contents of Al2O3 increased from 4.3% to 8.9 vol% as the milling time increased from 10 to 20 h. The increasing concentration led to the increase in Vickers hardness of Al2O3/TiAl composites, and a maximum value of 6.2 GPa was achieved. A corrected mixture rule was constructed which can predict the hardness of the composites accurately. The ultimate compression strength (UCS) increased firstly and then decreased with prolonging milling time. The highest value of 1848 MPa was obtained when the mixed powders milled for 15 h, i.e., the fraction of Al2O3 in the TiAl matrix was 7.6 vol%.