add six new materials

src/data/example.json

@@ -19,7 +19,8 @@
   "Electromagnetic Data": {
     "chi_m": [16.5e-6, "cm³/mol"],
     "sigma": ["16-18", "m/Ω/mm²"],
-    "epsilon_r": ["7±1", "F/m"]
+    "epsilon_r": ["7±1", "F/m"],
+    "mu_r": [">=1.005"]
   },
   "Mechanical Properties": {
     "T": ["20-25", "°C"],
@@ -29,6 +30,7 @@
     "K": [70, "GPa"],
     "nu": 0.35,
     "Yield strength": {
+      "R_p": ["110-130", "MPa"],
       "R_p02": ["110-130", "MPa"]
     },
     "R_m": ["230-290", "MPa"],
@@ -46,6 +48,7 @@
       "AH": 2,
       "ASA": 4
     },
+    "Vacuum": "yes",
     "Annotation": "T_Max<10h = 500 °C; T_Max>=10h = 450 °C"
   },
   "Heat treatment": {