A yttrium-containing high-temperature titanium alloy(Ti-6Al-2.7Sn-4Zr-0.4Mo-0.45Si-0.1Y, mass fraction, %) has been additively manufactured using selective electron beam melting(SEBM). The resulting microstructure and...A yttrium-containing high-temperature titanium alloy(Ti-6Al-2.7Sn-4Zr-0.4Mo-0.45Si-0.1Y, mass fraction, %) has been additively manufactured using selective electron beam melting(SEBM). The resulting microstructure and textures were studied using scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD) and electron backscattered diffraction(EBSD) and compared with the conventionally manufactured form. A notable distinct difference of microstructures is that additive manufacturing by SEBM enables homogeneous precipitation of fine Y2O3 dispersoids in the size range of 50-250 nm throughout the as-fabricated alloy, despite the presence of just trace levels of oxygen(7×10-4, mass fraction) and yttrium(10-3, mass fraction) in the alloy. In contrast, the conventionally manufactured alloy shows inhomogeneously distributed coarse Y2O3 precipitates, including cracked or debonded Y2O3 particles.展开更多
由于存在大的温度梯度,激光熔化沉积过程会沿沉积方向形成具有择优取向的粗大柱状晶,导致材料产生显著的各向异性。拟通过在钛合金中添加Cu以实现改变初生β晶粒形态、细化组织并弱化织构的目的。系统研究了不同含量的Cu添加对激光熔化...由于存在大的温度梯度,激光熔化沉积过程会沿沉积方向形成具有择优取向的粗大柱状晶,导致材料产生显著的各向异性。拟通过在钛合金中添加Cu以实现改变初生β晶粒形态、细化组织并弱化织构的目的。系统研究了不同含量的Cu添加对激光熔化沉积TC4钛合金组织及织构的影响,结果表明,Cu元素能够显著细化柱状初生β晶粒,并使晶粒尺寸分布更加均匀,Cu元素添加量为4%(质量分数,下同)时能够实现完全的柱状晶向等轴晶转变,平均晶粒尺寸由未添加时的1490μm降低到385μm。添加Cu试样的晶粒内部仍为网篮组织,主要由α-Ti、β-Ti和少量Ti2Cu相组成,其中Ti2Cu呈短棒状分布在α-Ti板条的边界处,其在组织中的占比随Cu添加量的增大而增加。当添加8%Cu时,α-Ti的平均宽度为0.44μm,与未添加Cu试样的1.18μm相比降低了约63%。Cu添加能够显著降低激光熔化沉积钛合金的织构强度,当添加4%Cu时,α-Ti极图均匀分布倍数(multiples of uniform distribution,MUD)的最大值相比TC4降低了约71%。展开更多
基金Projects(2014KTZB01-02-03,2014KTZB01-02-04)supported by Shaanxi Science and Technology Coordination and Innovation Program,ChinaProject(DP120101672)supported by Australian Research Council(ARC)Discovery Grant,ARC Centre of Excellence for Design in Light Metals,Australia
文摘A yttrium-containing high-temperature titanium alloy(Ti-6Al-2.7Sn-4Zr-0.4Mo-0.45Si-0.1Y, mass fraction, %) has been additively manufactured using selective electron beam melting(SEBM). The resulting microstructure and textures were studied using scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD) and electron backscattered diffraction(EBSD) and compared with the conventionally manufactured form. A notable distinct difference of microstructures is that additive manufacturing by SEBM enables homogeneous precipitation of fine Y2O3 dispersoids in the size range of 50-250 nm throughout the as-fabricated alloy, despite the presence of just trace levels of oxygen(7×10-4, mass fraction) and yttrium(10-3, mass fraction) in the alloy. In contrast, the conventionally manufactured alloy shows inhomogeneously distributed coarse Y2O3 precipitates, including cracked or debonded Y2O3 particles.
文摘由于存在大的温度梯度,激光熔化沉积过程会沿沉积方向形成具有择优取向的粗大柱状晶,导致材料产生显著的各向异性。拟通过在钛合金中添加Cu以实现改变初生β晶粒形态、细化组织并弱化织构的目的。系统研究了不同含量的Cu添加对激光熔化沉积TC4钛合金组织及织构的影响,结果表明,Cu元素能够显著细化柱状初生β晶粒,并使晶粒尺寸分布更加均匀,Cu元素添加量为4%(质量分数,下同)时能够实现完全的柱状晶向等轴晶转变,平均晶粒尺寸由未添加时的1490μm降低到385μm。添加Cu试样的晶粒内部仍为网篮组织,主要由α-Ti、β-Ti和少量Ti2Cu相组成,其中Ti2Cu呈短棒状分布在α-Ti板条的边界处,其在组织中的占比随Cu添加量的增大而增加。当添加8%Cu时,α-Ti的平均宽度为0.44μm,与未添加Cu试样的1.18μm相比降低了约63%。Cu添加能够显著降低激光熔化沉积钛合金的织构强度,当添加4%Cu时,α-Ti极图均匀分布倍数(multiples of uniform distribution,MUD)的最大值相比TC4降低了约71%。
