## 2 Materials and Methods  
In this study, the Ti-6 Al-4V specimens were produced from two kinds of starting materials, blended and prealloyed powders. The blended Ti-6 Al-4V was prepared by blending of commercial pure (CP) Ti powder (99.8%, \(-\)325 mesh), Al powder (99.5%, \(-\)500 mesh), and 35 Al65V powder (99.5%, \(-\)325 mesh). For comparison, gas atomization (GA) Ti-6 Al-4V powder (99.8%, \(-\)325 mesh) was used to fabricated Ti-6 Al-4V parts as well. The fabricated Ti-6 Al-4V starting from blended and prealloyed powders are designated as B and P samples in the following paragraphs, respectively.  
Feedstocks were prepared by mixing the starting powders with binders in a \(Z\)-blade kneader at 190 \({}^{\circ}\)C with a powder loading of 60 vol%. To achieve a homogeneous feedstock, the B powder was kneaded with binders for 60 min while the P powder was kneaded with binders for 30 min. The binder system used in this study consisted of polyformaldehyde(POM), stearic acid (SA), paraffin wax (PW), ethylene vinyl acetate (EVA), and polyethylene (PE). The feedstocks were then granulated, and injection molded using an injection molding machine (Nissei Nex 80 IIIT, Nagano-ken, Japan). In order to measure the mechanical properties, \"dog-bone\" tensile bars with a nominal length of 90 mm and a gauge diameter of 5 mm were fabricated. After injection molding, the green samples were debound in two steps. Firstly, most of the polyformaldehyde was removed in the catalytic debinding process, which was carried out at 120 \({}^{\circ}\)C for 240 min in a catalytic debinding furnace (SinterZone, Shenzhen, China) with a nitric acid vapor flow of \(\sim\)2 g/min. After that, thermal debinding for final removal of the remaining binders and subsequent sintering were carried out in a single-step heat treatment run, using a MIM furnace (Hiper vacuum, Ningbo, China). Sintering was conducted under flowing argon at 1200 \({}^{\circ}\)C for 180 min and 1300 \({}^{\circ}\)C for 120 min, respectively, followed by controlled furnace cooling.  
The viscosity of the feedstock was measured using a capillary rheometer (Gottfert RG20, Buchen, Germany). A die with diameter of 1 mm and length of 30 mm was selected. The cavity of the rheometer was heated to 190 \({}^{\circ}\)C during measurement. The chemical reaction in B green sample during heating was analyzed by thermogravimetry (TG) and differential scanning calorimeter (DSC) in a simultaneous thermal analyzer (Netzsch STA 449 F3, Selb, Germany), where a green sample was scanned from room temperature to 1250 \({}^{\circ}\)C with a heating rate of 10 \({}^{\circ}\)C/min in argon atmosphere. The density of the sintered Ti-6 Al-4V was measured by the Archimedes water immersion method in a density balance ([PERSON], Goettingen, Germany). The impurity levels of the samples, such as levels of oxygen, nitrogen, and carbon, were determined using the melt extraction method in element composition analyzers (Leco ON736 and CS744, Saint Joseph, MI, USA). The tensile tests were conducted on sintered samples at room temperature at a strain rate of 3.3 \(\times\) 10\({}^{-4}\) s\({}^{-1}\) using a universal test machine (Sans CMT5504, Zhuhai, China). For metallographic examination, samples were cut from the center of the sintered tensile test bar. An etching reagent (2 mL HF, 5 mL H\({}_{2}\)O\({}_{2}\) in 100 mL H\({}_{2}\)O) was used to etch the samples for optical metallography. The pore distribution and grain size of the sintered parts were observed by an optical microscope (Leica, Wetzlar, Germany). The powder morphology and fracture surfaces of green and sintered samples were observed using a scanning electron microscope (SEM, Zeiss EVO-10, Jena, Germany).