Critical niobium content in the compression performance and post-peak stability of porous Ti6Al–Nb alloys

Abstract In this study, the effect of niobium (Nb) addition on the compressive properties of porous Ti6AlxNb ( x = 0, 2, 4, 8 wt.%) alloys produced by powder metallurgy was investigated using experimental and multivariate statistical analysis. Porous Ti6Al4V alloy was used as the reference material. Force–displacement data from compression tests were processed using a data-driven approach including quality control, common grid resampling, and metric extraction. Results show that Nb addition significantly affects the ultimate compressive strength (UCS) and post-peak deformation behavior. The Ti6Al alloy without Nb exhibits a sharp stress drop at 303.7 MPa, whereas alloys containing ≥ 4 wt.% Nb show stable post-peak deformation with strengths around 335 MPa. Toughness and energy absorption increase with Nb content; Ti6Al8Nb shows about 69 % higher energy absorption than Ti6Al. However, the addition of 2 wt.% Nb reduces strength, indicating a critical compositional threshold. Principal component analysis shows that the first two components explain 92.4 % of the total variance. Alloys with ≥ 4 wt.% Nb approach the mechanical performance of the reference Ti6Al4V alloy, indicating that Nb addition improves deformation stability and energy absorption in porous Ti-based alloys.