In order to develop the liquid phase sintering process of WC-Ni3Al-B composites,the preparation process of WC＋Ni3Al prealloyed powder by reaction synthesis of carbonyl Ni,analytical purity Al and coarse WC powders wa...In order to develop the liquid phase sintering process of WC-Ni3Al-B composites,the preparation process of WC＋Ni3Al prealloyed powder by reaction synthesis of carbonyl Ni,analytical purity Al and coarse WC powders was investigated.DSC and XRD were adopted to study the procedure of phase transformation for the 3Ni＋Al and 70%WC＋（3Ni＋Al） mixed powders in temperature ranges of 550-1200 °C and 25-1400 °C,respectively.The results demonstrate that the formation mechanism of Ni3Al depends on the reaction temperature.Besides WC phase,there exist Ni2Al3,NiAl and Ni3Al intermetallics in the powder mixture after heat treatment at 200-660 °C,while only NiAl and Ni3Al exist at 660-1100 °C.Homogeneous WC＋Ni3Al powder mixture can be obtained in the temperature range of 1100-1200 °C.The WC-30%（Ni3Al-B） composites prepared from the mixed powders by conventional powder metallurgy technology show nearly full density and the shape of WC is round.WC-30%（Ni3Al-B） composites exhibit higher hardness of 9.7 GPa,inferior bending strength of 1800 MPa and similar fracture toughness of 18 MPa-m1/2 compared with commercial cemented carbides YGR45（WC-30%（Co-Ni-Cr））.展开更多
应用美国LECO公司TCH600氧氮氢分析仪对WC-Ni_3Al中氧的测定条件进行试验和研究。试验结果表明,选择石墨套坩埚、分析功率4.0 k W、分析积分时间40 s为最佳测定条件。在优化条件下建立氧校正曲线,线性好,相关系数大于0.9990。测定氧含量...应用美国LECO公司TCH600氧氮氢分析仪对WC-Ni_3Al中氧的测定条件进行试验和研究。试验结果表明,选择石墨套坩埚、分析功率4.0 k W、分析积分时间40 s为最佳测定条件。在优化条件下建立氧校正曲线,线性好,相关系数大于0.9990。测定氧含量为0.15%的样品,相对标准偏差(RSD,n=11)为1.9%,完全满足生产和科研的需要。展开更多
This study evaluated the mechanical properties and thermal properties of Al-12 vol%B4 C composite at elevated temperature strengthened with in situ Al2 O3 network.The composite was fabricated using powder metallurgy(P...This study evaluated the mechanical properties and thermal properties of Al-12 vol%B4 C composite at elevated temperature strengthened with in situ Al2 O3 network.The composite was fabricated using powder metallurgy(PM)with raw materials of fine atomized aluminum powders,and the associated microstructures were observed.At 350℃,the composite had ultimate tensile strength of UTS=137 MPa,yield strength of YS0.2=118 MPa,and elongation ofε=4%.Besides,the mechanical properties of the composite remained unchanged at 350℃after the long holding periods up to 1000 h.The excellent mechanical properties and thermal stability at 350℃were secured by in situ am-Al2O3 network that strengthened the grain boundaries.The interfacial debonding and brittle cracking of B4 C particles were the main fracture mechanisms of the composite.In addition,the influence of sintering temperature and rolling deformation on the microstructures and mechanical properties was studied.展开更多
基金Project (2012CB723906) supported by the National Basic Research Program of China
文摘In order to develop the liquid phase sintering process of WC-Ni3Al-B composites,the preparation process of WC＋Ni3Al prealloyed powder by reaction synthesis of carbonyl Ni,analytical purity Al and coarse WC powders was investigated.DSC and XRD were adopted to study the procedure of phase transformation for the 3Ni＋Al and 70%WC＋（3Ni＋Al） mixed powders in temperature ranges of 550-1200 °C and 25-1400 °C,respectively.The results demonstrate that the formation mechanism of Ni3Al depends on the reaction temperature.Besides WC phase,there exist Ni2Al3,NiAl and Ni3Al intermetallics in the powder mixture after heat treatment at 200-660 °C,while only NiAl and Ni3Al exist at 660-1100 °C.Homogeneous WC＋Ni3Al powder mixture can be obtained in the temperature range of 1100-1200 °C.The WC-30%（Ni3Al-B） composites prepared from the mixed powders by conventional powder metallurgy technology show nearly full density and the shape of WC is round.WC-30%（Ni3Al-B） composites exhibit higher hardness of 9.7 GPa,inferior bending strength of 1800 MPa and similar fracture toughness of 18 MPa-m1/2 compared with commercial cemented carbides YGR45（WC-30%（Co-Ni-Cr））.
文摘应用美国LECO公司TCH600氧氮氢分析仪对WC-Ni_3Al中氧的测定条件进行试验和研究。试验结果表明,选择石墨套坩埚、分析功率4.0 k W、分析积分时间40 s为最佳测定条件。在优化条件下建立氧校正曲线,线性好,相关系数大于0.9990。测定氧含量为0.15%的样品,相对标准偏差(RSD,n=11)为1.9%,完全满足生产和科研的需要。
基金financially supported by Shenzhen Engineering Laboratory of Nuclear Materials and Service Safety。
文摘This study evaluated the mechanical properties and thermal properties of Al-12 vol%B4 C composite at elevated temperature strengthened with in situ Al2 O3 network.The composite was fabricated using powder metallurgy(PM)with raw materials of fine atomized aluminum powders,and the associated microstructures were observed.At 350℃,the composite had ultimate tensile strength of UTS=137 MPa,yield strength of YS0.2=118 MPa,and elongation ofε=4%.Besides,the mechanical properties of the composite remained unchanged at 350℃after the long holding periods up to 1000 h.The excellent mechanical properties and thermal stability at 350℃were secured by in situ am-Al2O3 network that strengthened the grain boundaries.The interfacial debonding and brittle cracking of B4 C particles were the main fracture mechanisms of the composite.In addition,the influence of sintering temperature and rolling deformation on the microstructures and mechanical properties was studied.
