摘要
采用粉末注射成形工艺制备含钕的钛合金TixNd(x为Nd的质量分数,%),采用金相显微镜、扫描电镜、电子探针以及硬度和力学性能测试等分析手段,研究钕对注射成形钛合金中氧的分布及力学性能的影响,并分析钕的最佳添加量。结果表明:随钕含量增加,合金的密度和伸长率先增加后降低,其中Ti15Nd的性能最优异,其相对密度为98.2%,强度和伸长率分别达到634 MPa和6.5%,比纯钛分别提高248 MPa和6.5%。纯钛的断裂面呈现解理断裂特征,而Ti15Nd为延性断裂。添加钕能提高钛合金的致密度,并且钕能吸收周围钛基体中的氧原子形成氧化钕,调节TixNd合金中氧的分布,从而有效提高合金的强度和韧性。计算证明氧化钛的分解和氧化钕的形成在热力学上是可行的。建立Ti-Nd扩散模型,考虑钕的蒸发和氧化等因素,计算得出钕的最佳添加量(质量分数)约为4.3%。
TixNd alloys with different Nd contents were prepared by metal injection molding process. Effect of Nd on microstructure, mechanical properties, oxidation mechanism and the optimum amount of the prepared alloy were investigated by metallographic microscopy, scanning electron microscopy and electron microprobe as well as mechanical property and hardness testers. The results show that the density and elongation increase and then decrease with increasing Nd content, in which Ti15Nd has the most outstanding performance with relative density reaching 98.2%, the strength and elongation rate are reaching 634 MPa and 6.5%The fracture surface of pure titanium exhibits a cleavage fracture in tension, as for Ti15Nd specimens, the evidence of plastic deformation and dimpled rupture are observed. Under the sintering conditions, Nd powder melts to form a liquid and thus accelerate the densification. Nd can effectively absorb the oxygen atoms in titanium matrix, adjust the distribution of oxygen in the TixNd alloy and improve the ductility. Calculations prove that the decomposition of titanium oxide and formation of neodymium oxide are thermodynamically feasible. Establishing Ti-Nd diffusion model and considering the evaporation and oxidation of Nd, obtain the calculated optimal addition of Nd about 4.3wt.%.
出处
《粉末冶金材料科学与工程》
EI
北大核心
2014年第3期401-407,共7页
Materials Science and Engineering of Powder Metallurgy
基金
国家自然科学基金资助项目(51075405)
