Ti-6Al-4V合金表面的热氧化/真空扩散处理

利用热氧化后真空扩散处理工艺在Ti 6Al 4V合金表面制备了与基体结合良好的硬化层 ,并在空气和真空条件下分别进行了摩擦磨损试验。结果表明 ,硬化层由表面氧化物薄层和氧扩散区组成 ,硬化深度可达 6 0μm。经 84 0℃真空扩散后 ,在表面硬化层中发现有Ti3 Al相形成 ,使沿层深方向的硬度下降趋势变缓。热氧化 /真空扩散处理可有效地降低在空气和真空中的Ti 6Al 4V合金与GCr15钢的干摩擦因数 ,提高Ti 6Al

钛合金表面的热氧化/真空扩散处理工艺

采用热氧化后真空扩散处理工艺 ,在 Ti6Al4V合金表面制备了与基体结合良好的硬化层 ,并在空气和真空条件下分别进行了摩擦磨损试验。结果表明 ,硬化层由表面氧化物薄层和氧扩散区组成。经 81 0℃真空扩散后 ,在表面硬化层有 Ti3 Al相形成 ,使沿层深方向的硬度下降趋势变缓。热氧化 /真空扩散处理可有效地降低在空气和真空中的 Ti6Al4V合金与 GCr1 5钢的干摩擦系数 ,提高

Effect of bonding temperature and heat treatment on microstructure and mechanical property of Mg−6Gd−3Y alloy vacuum diffusion bonded joints

Diffusion bonding of as-cast Mg−6Gd−3Y magnesium alloy was carried out at temperatures of 400−480℃ with bonding pressure of 6 MPa for 90 min.Diffusion bonded joints were solution treated at 495℃ for 14 h and then aged at 200℃ for 30 h.Microstructures and mechanical properties of joints were analyzed.The results showed that rare earth elements and their compounds gathering at bonding interface hindered the grain boundary migration crossing bonding interface.Tensile strength of as-bonded and as-solution treated joints increased firstly and then decreased with the bonding temperature increasing due to the combined effects of grain coarsening and solid-solution strengthening.As-bonded and solution-treated joints fractured at matrix except the joint bonded at 400℃,while aged joints fractured at bonding interface.The highest ultimate tensile strength of 279 MPa with elongation of 2.8%was found in joint bonded at 440℃ with solution treatment followed by aging treatment.

DD98M纳米晶AlSi渗层制备及抗高温腐蚀性能研究

采用磁控溅射技术在DD98M合金表面制备了同成份的纳米晶,采用多弧离子镀技术在DD98M纳米晶涂层表面沉积了AlSi涂层,对上述制备态纳米晶+AlSi复合涂层进行了真空扩散处理,得到了外层为β-NiAl层、内层为γ'-Ni_3Al层的双层结构复合涂层。研究了合金、DD98M纳米晶涂层及复合涂层在1050℃恒温氧化及900℃下Na_2SO_4+25%K_2SO_4混合熔盐体系中的热腐蚀行为。结果表明:1050℃恒温氧化时,DD98M合金表面生成NiO,α-Al_2O_3,Ta_(0.8)O_2,CrTaO_4及NiAl_2O_4等组成的混合氧化物膜,氧化膜开裂剥落严重。纳米晶涂层表面生成α-Al_2O_3和少量NiAl_2O_4组成的混合氧化物膜,复合涂层表面形成了均匀致密的单一α-Al_2O_3膜。纳米晶涂层和复合涂层大幅提高了合金的抗恒温氧化性能。在900℃下Na_2SO_4+25%K_2SO_4熔盐中,DD98M合金20 h后即发生了灾难性腐蚀,沉积态纳米晶及其预氧化涂层提高了合金的抗热腐蚀性能,复合涂层大幅提高了合金的抗热腐蚀性能。