This research focuses on studying the mechanical, tribological, and corrosion behaviors of alloy steels: AISI 4340, AISI 5140, and AISI 8620 by laser hardening, respectively. In light of the tests which have been carried out meticulously, it is concluded that the optimum laser hardening parameter for all steel grades is 4 mm/s scanning speed and 1300?C surface temperature. Micro-structural changes, Vickers hardness as mechanical properties, and tribological properties with reciprocating wear tests were carried out. Furthermore, corrosion tests were conducted. The test results reveal that the maximum hardness is achieved 50-300 ?m below the surface for all laser-hardened steels. Additionally, this study demonstrates that the wear resistance of steel is enhanced by the implementation of laser hardening. This study also determines that laser hardening has a positive impact on lifting the corrosion resistance behavior of AISI 4340 steel. In contrast, the corrosion resistance properties of AISI 8620 steel were reduced nearly by 54.17%.

This study investigated the microstructures, mechanical performances, corrosion resistances, and in vitro studies of porous Ti-xNb-10Zr (x: 10 and 20; at. %) alloys. The alloys were fabricated by powder metallurgy with two categories of porosities, i.e., 21–25% and 50–56%, respectively. The space holder technique was employed to generate the high porosities. Microstructural analysis was performed by using various methods including scanning electron microscopy, energy dispersive spectroscopy, electron backscatter diffraction, and x-ray diffraction. Corrosion resistance was assessed via electrochemical polarisation tests, while mechanical behavior was determined by uniaxial compressive tests. In vitro studies, such as cell viability and proliferation, adhesion potential, and genotoxicity, were examined by performing an MTT assay, fibronectin adsorption, and plasmid-DNA interaction assay. Experimental results showed that the alloys had a dual-phase microstructure composed of finely dispersed acicular hcp α-Ti needles in the bcc β-Ti matrix. The ultimate compressive strength ranged from 1019 MPa to 767 MPa for alloys with 21–25% porosities and from 173 MPa to 78 MPa for alloys with 50–56% porosities. Noted that adding a space holder agent played a more critical role in the mechanical behaviors of the alloys compared to adding niobium. The pores were largely open and exhibited irregular shapes, with uniform size distribution, allowing for cell ingrowth. Histological analysis showed that the alloys studied met the biocompatibility criteria required for orthopaedic biomaterial use.