5. Proposed Research Questions and Tasks
Four proposed research tasks will direct to fabrication conditions (Task 1), fabrication thermal analysis (Task 2), fabricated parts performance (Task 3), microstructure control methodology (Task 4), respectively. These tasks are designed to answer the questions and solve the problems in the results of preliminary experiments and observations from reported investigations.
5.1. Task 1. Investigating feasible formation conditions and effects of laser power and B content on ultrafine 3DQCN microstructure.
5.1.1. Research questions generation
In the TMCs manufacturing, fabrication energy and reinforcement content are two significant input variables [1,9,11], which are related to laser power and B content in laser deposition. Based on the preliminary results (Figure 6 in §4.5), laser deposition with low level of laser power could fabricate the 3D TMC parts, however, the 3DQCN microstructure was not found inside the parts. Low laser power led to poor fluidity of molten material, which would restrict movement of the in-situ reacted TiB whiskers. It also can be seen from Figure 6(a) that large-sized primary TiB was also formed at the low level of laser power, which would impede the formation …show more content…
Based on these results, 3DQCN microstructure initiation conditions and locations will also be found, which may provide additional explanations for formation of 3DQCN microstructure. It can contribute to testing effects of 3DQCN microstructural characterizations on mechanical properties. The experimental investigations in the rest proposed tasks will be conducted using combinations of input variables within the feasible regions.
5.2. Task 2: Analyzing Ti and B exothermic reaction energy and its influences on characterizations in the molten pool.
5.2.1. Research question
Four proposed research tasks will direct to fabrication conditions (Task 1), fabrication thermal analysis (Task 2), fabricated parts performance (Task 3), microstructure control methodology (Task 4), respectively. These tasks are designed to answer the questions and solve the problems in the results of preliminary experiments and observations from reported investigations.
5.1. Task 1. Investigating feasible formation conditions and effects of laser power and B content on ultrafine 3DQCN microstructure.
5.1.1. Research questions generation
In the TMCs manufacturing, fabrication energy and reinforcement content are two significant input variables [1,9,11], which are related to laser power and B content in laser deposition. Based on the preliminary results (Figure 6 in §4.5), laser deposition with low level of laser power could fabricate the 3D TMC parts, however, the 3DQCN microstructure was not found inside the parts. Low laser power led to poor fluidity of molten material, which would restrict movement of the in-situ reacted TiB whiskers. It also can be seen from Figure 6(a) that large-sized primary TiB was also formed at the low level of laser power, which would impede the formation …show more content…
Based on these results, 3DQCN microstructure initiation conditions and locations will also be found, which may provide additional explanations for formation of 3DQCN microstructure. It can contribute to testing effects of 3DQCN microstructural characterizations on mechanical properties. The experimental investigations in the rest proposed tasks will be conducted using combinations of input variables within the feasible regions.
5.2. Task 2: Analyzing Ti and B exothermic reaction energy and its influences on characterizations in the molten pool.
5.2.1. Research question